Image display and method for manufacturing image display

ABSTRACT

In a first aspect of the invention, an image display device, in which one or more groups of particles or liquid powders are sealed between opposed two substrates, at least one of two substrates being transparent, and, in which the particles or the liquid powders, to which an electrostatic field produced by two groups of electrodes having different potentials is applied, are made to move so as to display an image, has a construction such that a member for transmitting a signal, which is applied to circuits for an image display, is provided to the substrate by means of an anisotropic conductive film and members such as the electrode are provided to a substrate opposed to a transparent substrate. In second to sixth aspects of the invention, an image display device has a construction such that the electrode is arranged to a surface of the substrate through a transparent elastic member, or, an anti-reflection layer is arranged, or, a connection operation between two substrates through a partition wall is optimized.

TECHNICAL FIELD

The present invention relates to an image display device, whichcomprises an image display panel enables to repeatedly display or deleteimages accompanied by flight and movement of particles utilizingCoulomb's force and so on, and a method of manufacturing the same.

BACKGROUND ART

As an image display device substitutable for liquid crystal display(LCD), image display devices with the use of technology such as anelectro-phoresis method, an electro-chromic method, a thermal method,dichroic-particles-rotary method are proposed.

As for these image display device, it is conceivable as inexpensivevisual display device of the next generation from a merit having widefield of vision close to normal printed matter, having smallerconsumption with LCD, spreading out to a display for portable device,and an electronic paper is expected. Recently, electrophoresis method isproposed that microencapsulate dispersion liquid made up with dispersionparticles and coloration solution and dispose the liquid between facedsubstrates.

However, in the electrophoresis method, there is a problem that aresponse rate is slow by the reason of viscosity resistance because theparticles migrate among the electrophoresis solution. Further, there isa problem of lacking imaging repetition stability, because particleswith high specific gravity of titanium oxide is scattered withinsolution of low specific gravity, it is easy to subside, difficult tomaintain a stability of dispersion state. Even in the case ofmicroencapsulating, cell size is diminished to a microcapsule level inorder to make it hard to appear, however, an essential problem was notovercome at all.

Besides the electrophoresis method using behavior in the solution,recently, a method wherein electro-conductive particles and a chargetransport layer are installed in a part of the substrate without usingsolution is proposed. [The Imaging Society of Japan “Japan Hardcopy '99”(Jul. 21-23, 1999) Transaction Pages 249-252] However, the structurebecomes complicated because the charge transport layer and further acharge generation layer are to be arranged. In addition, it is difficultto constantly dissipate charges from the electro-conductive particles,and thus there is a drawback on the lack of stability (common tasks tobe solved by first to sixth aspects of the invention).

Moreover, when an electrode is provided in the image display device, ittakes a long time to provide the electrode according to the knownmethod. Therefore, there is a drawback such that a manufacturingefficiency of the image display device is low and further a substrate isadversely affected due to heating (task to be solved by the first aspectof the invention).

Further, when such a dry-type display plate is integrated with anoptical function member having an anti-reflection function or a touchpanel function and used as ATM or CD in the bank, a portable informationterminal, a mobile phone, a display for computer and so on, there is adrawback such that a clear image is not obtained (task to be solved bythe second aspect of the invention).

Moreover, it is required to achieve a high contrast image by increasinga light transmittance and to improve a visibility so as to obtain a highcontrast image. However, there is a drawback such that some requirementsare not achieved (task to be solved by the third aspect of theinvention).

Further, as one method of solving various problems mentioned above, itis known an image display device which comprises an image display panel,in which two or more groups of particles or liquid powders havingdifferent colors and different charge characteristics are sealed betweentwo substrates, at least one of two substrates being transparent, and,in which the particles or the liquid powders, to which an electrostaticfield produced by a pair of electrodes having different potentials isapplied, are made to move by means of Coulomb's force so as to displayan image. In the image display device mentioned above, since it is adry-type, it is possible to achieve rapid response, simple construction,inexpensive cost and excellent image stability. However, since it usesthe particles or the liquid powders for the image displaying, there is adrawback such that it is difficult to eliminate a positional deviationbetween the substrates and a leakage of the particles or the liquidpowders by sealing two substrates by means of adhesives under thecondition such that the particles or the liquid powders are existentbetween them (task to be solved by the fourth aspect of the invention).

Moreover, in order to solve the problems mentioned above, as an imagedisplay device of dry-type having rapid response, simple construction,inexpensive cost and excellent stability, it is known an image displaydevice which comprises an image display panel, in which two groups ofparticles or liquid powders having different colors and different chargecharacteristics are sealed between a transparent substrate and anopposed substrate, and, in which the particles or the liquid powders, towhich an electrostatic field produced by two groups of electrodes havingdifferent potentials is applied, are made to move so as to display animage. In the image display device, image display elements are formed byarranging partition walls between the transparent substrate and theopposed substrate.

In the image display device having the construction mentioned above, thepartition wall arrangement is performed by positioning the partitionwall between the transparent substrate and the opposed substrate andapplying adhesives to a corner portion between the substrate and thepartition wall. In this case, if use is made of a glass substrate as thetransparent substrate or the opposed substrate, a connection between thesubstrate and the partition wall has a sufficient strength. However, ifuse is made of other transparent resins, there is a drawback such that asufficient connection strength can not be obtained. Therefore, it is notpossible to eliminate a leakage of the particles or the liquid powderscompletely (task to be solved by the sixth aspect of the invention).

DISCLOSURE OF INVENTION

A first embodiment of a first aspect of the invention relates to a newtype image display device which is investigated to overcome the problemsmentioned above and has for its object to effectively manufacture theimage display device having an excellent performance, which can achievea rapid response, simple construction, inexpensive cost and excellentstability and further arrange electrodes in a short time.

The inventors perform various investigation and find that it is possibleto effectively manufacture the image display device having an excellentperformance by means of the following image display device. That is, inthe image display device, in which one or more groups of particles aresealed between opposed two substrates, at least one of two substratesbeing transparent, are made to move so as to display an image, ananisotropic conductive film in which conductive powders are scattered inan adhesive for connecting electrodes. The present invention is achievedby this finding.

According to the first embodiment of the first aspect of the invention,the following image display devices are provided:

-   1. An image display device, in which one or more groups of particles    are sealed between opposed two substrates, at least one of two    substrates being transparent, and, in which the particles, to which    an electrostatic field is applied, are made to move so as to display    an image, characterized in that a member for transmitting a signal,    which is supplied to circuits for an image display, is provided to    the substrate by means of an anisotropic conductive film;-   2. The image display device according to the above 1, wherein an    average particle diameter of the particles is 0.1-50 μm;-   3. The image display device according to the above 1 or 2, wherein    the difference of a surface charge density between two groups of the    particles measured by using the same kind of carrier in accordance    with a blow-off method is 5-150 μC/m²;-   4. The image display device according to one of the above 1-3,    wherein the particles are particles in which the maximum surface    potential, in the case that the surface of particles is charged by a    generation of Corona discharge caused by applying a voltage of 8 KV    to a Corona discharge device deployed at a distance of 1 mm from the    surface of the particles, is greater than 300 V at 0.3 second after    the Corona discharge;-   5. The image display device according to one of the above 1-4,    wherein the anisotropic conductive film is formed by scattering    conductive particles in a thermosetting adhesive or a photo-curing    adhesive;-   6. The image display device according to the above 5, wherein a    diameter of the conductive particles scattered in the thermosetting    adhesive or the photo-curing adhesive is 0.1-20 μm; and-   7. The image display device according to the above 5 or 6, wherein    the thermo-setting adhesive or the photo-curing adhesive includes    one or more groups of compounds having one of glycidyl group,    acrylic group and methacrylic group.

A second embodiment of a first aspect of the invention relates to a newdry type image display device which is investigated to overcome theproblems mentioned above and has for its object, in a device forrepeatedly display an image by utilizing an electrostatic, toeffectively manufacture the image display device having an excellentperformance, which can achieve inexpensive cost and excellent stabilityand further arrange electrodes in a short time.

The inventors perform various investigations and find that it ispossible to obtain new image display device which achieve rapidresponse, inexpensive cost, excellent stability and low driving voltage,by using liquid powders having a fluidity that is a feature of a liquidand a shape memory property that is a feature of a solid. Moreover, theinventors find that it is possible to effectively manufacture the imagedisplay device having an excellent performance by providing a member fortransmitting a signal, which is supplied to circuits for an imagedisplay, to the substrate by means of an anisotropic conductive film.The present invention is achieved by these findings.

According to the second embodiment of the first aspect of the invention,the following image display devices are provided:

-   1. An image display device, in which liquid powders, which indicate    a high fluidity in an aerosol state such that solid-like substances    are suspended in a gas stably as dispersoid, are sealed between    opposed two substrates, at least one of two substrates being    transparent, and, in which the liquid powders are made to move,    characterized in that a member for transmitting a signal, which is    applied to circuits for an image display, is provided to the    substrate by means of an anisotropic conductive film;-   2. The image display device according to the above 1, wherein an    apparent volume in a maximum floating state of the liquid powders is    two times or more than that in none floating state;-   3. The image display device according to the above 1 or 2, wherein a    time change of the apparent volume of the liquid powders satisfies    the following formula:    V ₁₀ /V ₅>0.8;    here, V₅ indicates the apparent volume (cm³) of the liquid powders    after 5 minutes from the maximum floating state; and V₁₀ indicates    the apparent volume (cm³) of the liquid powders after 10 minutes    from the maximum floating state;-   4. The image display device according to one of the above 1-3,    wherein an average particle diameter d(0.5) of the liquid powders is    0.1-20 μm;-   5. The image display device according to one of the above 1-4,    wherein the anisotropic conductive film is formed by scattering    conductive particles in a thermosetting adhesive or a photo-curing    adhesive;-   6. The image display device according to the above 5, wherein a    diameter of the conductive particles scattered in the thermosetting    adhesive or the photo-curing adhesive is 0.1-20 μm; and-   7. The image display device according to the above 5 or 6, wherein    the thermo-setting adhesive or the photo-curing adhesive includes    one or more groups of compounds having one of glycidyl group,    acrylic group and methacrylic group.

A first embodiment of a second aspect of the invention relates to animage display device using a dry type electrostatic display panel andhas for its object to provide the image display device having simpleconstruction and excellent stability, which is integrated with anoptical function member in which a sharp image can be obtained.

The inventors perform various investigations and find that, when animage display panel, in which one or more groups of particles are sealedbetween opposed two substrates, at least one of two substrates beingtransparent, and, in which the particles, to which an electrostaticfield produced by two groups of electrodes having different potentialsis applied, are made to move so as to display an image, and an opticalfunction member are integrated through a transparent layer, it ispossible to obtain simple construction, excellent stability and sharpimage. The present invention is achieved by this finding.

According to the first embodiment of the second aspect of the invention,the following image display devices are provided:

-   1. An image display device which comprises an image display panel    and an optical function member, in which one or more groups of    particles are sealed between opposed two substrates, at least one of    two substrates being transparent, and, in which the particles, to    which an electrostatic field produced by two groups of electrodes    having different potentials is applied, are made to move so as to    display an image, characterized in that the image display panel and    the optical function member are integrated through a transparent    elastic layer;-   2. The image display device according to the above 1, wherein an    average particle diameter of the particles is 0.1-50 μm;-   3. The image display device according to the above 1 or 2, wherein    the difference of a surface charge density in an absolute value    between two groups of the particles measured by using the same kind    of carrier in accordance with a blow-off method is 5-150 μC/m²;-   4. The image display device according to one of the above 1-3,    wherein the particles are particles in which the maximum surface    potential, in the case that the surface of particles is charged by a    generation of Corona discharge caused by applying a voltage of 8 KV    to a Corona discharge device deployed at a distance of 1 mm from the    surface of the particles, is greater than 300 V at 0.3 second after    the Corona discharge;-   5. The image display device according to one of the above 1-4,    wherein, when it is assumed that a refractive index of the    transparent elastic layer is n₀, a refractive index of the optical    function member is n₁ and a refractive index of the transparent    substrate is n₂, an absolute of a difference between n₀ and n₁ and    an absolute of a difference between n₀ and n₂ are not greater than    0.2 respectively; and-   6. The image display device according to one of the above 1-5,    wherein the transparent elastic layer has a property such that, when    it is assumed that a strain (ε₀) at 25° C. of a stress relaxation is    5% and an initial value (after 0.05 sec) of a stress relaxation    elastic modulus is G₀, G₀ is not greater than 6.5×10⁶ Pa, and, a    property such that a stress relaxation time τ calculated on the    basis of a formula:    InG(t)=−t/τ+InG ₀    showing a relation between a stress relaxation elastic modulus G and    a time t (sec.) obtained from a damping curve of the relaxation    elastic modulus, is not greater than 17 sec.

A second embodiment of a second aspect of the invention relates to a newdry type image display device which is investigated to overcome theproblems mentioned above and has for its object, in a method forrepeatedly display an image by utilizing an electrostatic, to providethe image display device having simple construction and excellentstability, which is integrated with an optical function member in whicha sharp image can be obtained.

The inventors perform various investigations and find that it ispossible to obtain an image display panel which achieve rapid response,inexpensive cost, excellent stability and low driving voltage, by usingliquid powders having a fluidity that is a feature of a liquid and ashape memory property that is a feature of a solid. Moreover, theinventors find that it is possible to obtain a new image display devicehaving a sharp image by integrating the image display panel mentionedabove and the optical function member through a transparent elasticlayer.

According to the second embodiment of the second aspect of theinvention, the following image display devices are provided:

-   1. An image display device which comprises an image display panel    and an optical function member, in which liquid powders, which    indicate a high fluidity in an aerosol state such that solid-like    substances are suspended in a gas stably as dispersoid, are sealed    between opposed two substrates, at least one of two substrates being    transparent, and, in which the liquid powders are made to move,    characterized in that the image display panel and the optical    function member are integrated through a transparent elastic layer;-   2. The image display device according to the above 1, wherein an    apparent volume in a maximum floating state of the liquid powders is    two times or more than that in none floating state;-   3. The image display device according to the above 1 or 2, wherein a    time change of the apparent volume of the liquid powders satisfies    the following formula:    V ₁₀ /V ₅>0.8;    here, V₅ indicates the apparent volume (cm³) of the liquid powders    after 5 minutes from the maximum floating state; and V₁₀ indicates    the apparent volume (cm³) of the liquid powders after 10 minutes    from the maximum floating state;-   4. The image display device according to one of the above 1-3,    wherein an average particle diameter d(0.5) of the liquid powders is    0.1-20 μm;-   5. The image display device according to one of the above 1-4,    wherein, when it is assumed that a refractive index of the    transparent elastic layer is n₀, a refractive index of the optical    function member is n₁ and a refractive index of the transparent    substrate is n₁, an absolute of a difference between n₀ and n₁ and    an absolute of a difference between n₀ and n₂ are not greater than    0.2 respectively; and-   6. The image display device according to one of the above 1-5,    wherein the transparent elastic layer has a property such that, when    it is assumed that a strain (ε₀) at 25° C. of a stress relaxation is    5% and an initial value (after 0.05 sec) of a stress relaxation    elastic modulus is G₀, G₀ is not greater than 6.5×10⁶ Pa, and, a    property such that a stress relaxation time τ calculated on the    basis of a formula:    InG(t)=−t/τ+InG ₀    showing a relation between a stress relaxation elastic modulus G and    a time t (sec.) obtained from a damping curve of the relaxation    elastic modulus, is not greater than 17 sec.

A first embodiment of a third aspect of the invention relates to a drytype electrostatic display device and has for its object to provide theimage display device having simple construction and excellent stability,which can achieve a high contrast by increasing a light transmission andobtain a sharp image.

The inventors perform various investigations and find that, when plurallayers each indicating different refractive index are arranged on asurface of a transparent substrate of an image display device, in whichone or more groups of particles are sealed between opposed twosubstrates, at least one of two substrates being transparent, and, inwhich the particles, to which an electrostatic field produced by twogroups of electrodes having different potentials is applied, are made tomove so as to display an image, it is possible to obtain simpleconstruction, excellent stability, light transmission increase due to asuppression of outside light reflection, high contrast and sharp image.

According to the first embodiment of the third aspect of the invention,the following image display devices are provided:

-   1. An image display device, in which one or more groups of particles    are sealed between opposed two substrates, at least one of two    substrates being transparent, and, in which the particles, to which    an electrostatic field produced by two groups of electrodes having    different potentials is applied, are made to move so as to display    an image, characterized in that an anti-reflection layer having    plural layers each indicating different refractive index is arranged    on a surface of the transparent substrate;-   2. The image display device according to the above 1, wherein an    average particle diameter of the particles is 0.1-50 μm;-   3. The image display device according to the above 1 or 2, wherein    the difference of a surface charge density in an absolute value    between two groups of the particles measured by using the same kind    of carrier in accordance with a blow-off method is 5-150 μC/m²;-   4. The image display device according to one of the above 1-3,    wherein the particles are particles in which the maximum surface    potential, in the case that the surface of particles is charged by a    generation of Corona discharge caused by applying a voltage of 8 KV    to a Corona discharge device deployed at a distance of 1 mm from the    surface of the particles, is greater than 300 V at 0.3 second after    the Corona discharge;-   5. The image display device according to one of the above 1-4,    wherein the anti-reflection layer is constructed by stacking a low    reflection layer produced by a sputtering process using a conductive    silicon carbide as a target and a high reflection layer produced by    a sputtering process using a conductive titanium oxide as a target;    and-   6. The image display device according to the above 5, wherein the    anti-reflection layer prevents a light reflection of which    wavelength is 380-780 nm and a light reflection rate is not greater    than 10%.

A second embodiment of a third aspect of the invention relates to a newdry type image display device which is investigated to overcome theproblems mentioned above and has for its object, in a method forrepeatedly display an image by utilizing an electrostatic, to providethe image display device having simple construction and excellentstability, which can achieve a high contrast by increasing a lighttransmission and obtain a sharp image.

The inventors perform various investigations and find that it ispossible to obtain an image display device which achieve rapid response,inexpensive cost and excellent stability, by using liquid powders havinga fluidity that is a feature of a liquid and a shape memory propertythat is a feature of a solid. Moreover, the inventors find that it ispossible to improve a visibility since a sharp image can be obtained byarranging an anti-reflection layer to a transparent substrate. Thepresent invention is achieved by theses findings.

According to the second embodiment of the third aspect of the invention,the following image display devices are provided:

-   1. An image display device, in which liquid powders, which indicate    a high fluidity in an aerosol state such that solid-like substances    are suspended in a gas stably as dispersoid, are sealed between    opposed two substrates, at least one of two substrates being    transparent, and, in which the liquid powders are made to move,    characterized in that an anti-reflection layer having plural layers    each indicating different refractive index is arranged on a surface    of the transparent substrate;-   2. The image display device according to the above 1, wherein an    apparent volume in a maximum floating state of the liquid powders is    two times or more than that in none floating state;-   3. The image display device according to the above 1 or 2, wherein a    time change of the apparent volume of the liquid powders satisfies    the following formula:    V ₁₀ /V ₅>0.8;    where, V₅ indicates the apparent volume (cm³) of the liquid powders    after 5 minutes from the maximum floating state; and V₁₀ indicates    the apparent volume (cm³) of the liquid powders after 10 minutes    from the maximum floating state;-   4. The image display device according to one of claims 1-3, wherein    an average particle diameter d(0.5) of the liquid powders is 0.1-20    μm;-   5. The image display device according to one of claims 1-4, wherein    the anti-reflection layer is constructed by stacking a low    reflection layer produced by a sputtering process using a conductive    silicon carbide as a target and a high reflection layer produced by    a sputtering process using a conductive titanium oxide as a target;    and-   6. The image display device according to one of claims 1-5, wherein    the anti-reflection layer prevents a light reflection of which    wavelength is 380-780 nm and a light reflection rate is not greater    than 10%.

A first embodiment of a fourth aspect of the invention relates to a drytype image display device having rapid response, simple construction,inexpensive cost and excellent stability and has for its object toprovide the image display device comprising an image display panel whichcan achieve no positional deviation between substrates, prevent aleakage of particles and obtain a high image display accuracy.

According to the first embodiment of the fourth aspect of the invention,an image display device which comprises an image display panel, in whichtwo or more groups of particles having different colors and differentcharge characteristics are sealed between opposed two substrates, atleast one of two substrates being transparent, and, in which theparticles, to which an electrostatic field produced by a pair ofelectrodes arranged on one substrate or both substrates is applied, aremade to move so as to display an image, is characterized in that twosubstrates of the image display panel are connected by using athermosetting adhesive or a photo-curing adhesive.

In the image display panel used in the image display device according tothe first embodiment of the fourth aspect of the invention, since twosubstrates i.e. a transparent substrate and an opposed substrate areconnected by using the thermosetting adhesive or the photo-curingadhesive, it is possible to harden the adhesive in a short time byapplying a heat or irradiating a light after setting two substratesthrough the adhesive at a predetermined position. As a result, it ispossible to prevent the positional deviation between the substrates andthe leakage of the particles. Moreover, it is possible to achieve thehigh image display accuracy of the image display panel.

In the image display device according to the first embodiment of thefourth aspect of the invention, it is preferred that the thermosettingadhesive or the photo-curing adhesive includes one or more groups ofcompounds having one of glycidyl group, acrylic group and methacrylicgroup. Moreover, it is preferred that wherein an average particlediameter of the particles is 0.1-50 μm. Further, it is preferred thatthe difference of a surface charge density in an absolute value betweentwo groups of the particles measured by using the same kind of carrierin accordance with a blow-off method is 5-150 μC/m². Furthermore, it ispreferred that the particles are particles in which the maximum surfacepotential, in the case that the surface of particles is charged by ageneration of Corona discharge caused by applying a voltage of 8 KV to aCorona discharge device deployed at a distance of 1 mm from the surfaceof the particles, is greater than 300 V at 0.3 second after the Coronadischarge.

A second embodiment of a fourth aspect of the invention relates to animage display device having rapid response, inexpensive cost, improvedstability and a low driving voltage and has for its object to providethe image display device comprising an image display panel which canachieve no positional deviation between the substrates, prevent aleakage of liquid powders and obtain a high image display accuracy.

According to the second embodiment of the fourth aspect of theinvention, an image display device which comprises an image displaypanel, in which liquid powders, which indicate a high fluidity in anaerosol state such that solid-like substances are suspended in a gasstably as dispersoid, are sealed between opposed two substrates, atleast one of two substrates being transparent, and, in which the liquidpowders, to which an electrostatic field produced by a pair ofelectrodes arranged on one substrate or both substrates is applied, aremade to move so as to display an image, is characterized in that twosubstrates of the image display panel are connected by using athermosetting adhesive or a photo-curing adhesive.

In the image display panel used in the image display device according tothe second embodiment of the fourth aspect of the invention, since twosubstrates i.e. a transparent substrate and an opposed substrate areconnected by using the thermosetting adhesive or the photo-curingadhesive, it is possible to harden the adhesive in a short time byapplying a heat or irradiating a light after setting two substratesthrough the adhesive at a predetermined position. As a result, it ispossible to prevent the positional deviation between the substrates andthe leakage of the liquid powders. Moreover, it is possible to achievethe high image display accuracy of the image display panel.

In the image display device according to the second embodiment of thefourth aspect of the invention, it is preferred that the thermosettingadhesive or the photo-curing adhesive includes one or more groups ofcompounds having one of glycidyl group, acrylic group and methacrylicgroup. Moreover, it is preferred that an apparent volume in a maximumfloating state of the liquid powders is two times or more than that innone floating state. Further, it is preferred that a time change of theapparent volume of the liquid powders satisfies the following formula:V ₁₀ /V ₅>0.8;here, V₅ indicates the apparent volume (cm³) of the liquid powders after5 minutes from the maximum floating state; and V₁₀ indicates theapparent volume (cm³) of the liquid powders after 10 minutes from themaximum floating state. Furthermore, it is preferred that an averageparticle diameter d(0.5) of the liquid powders is 0.1-20 μm.

A first embodiment of a fifth aspect of the invention relates to a drytype image display device having rapid response, simple construction,inexpensive cost and excellent stability and has for its object toprovide the image display device which can make a display area largerand achieve a simple handling of the particles during the manufacturing.

According to the first embodiment of the fifth aspect of the invention,an image display device which comprises an image display panel, in whichtwo or more groups of particles having different colors and differentcharacteristics are sealed between opposed one substrate, at least oneof two substrates being transparent, and, in which the particles, towhich an electrostatic field produced by two groups of electrodes havingdifferent potentials is applied, are made to move so as to display animage, is characterized in that one or more image display elements areformed by using a partition wall and the partition wall has such a shapethat a bottom width wb at a side of an opposed substrate is larger thana top width wt at a side of a transparent substrate.

In the first embodiment of the fifth aspect of the invention, since thepartition wall has such a shape that the bottom width wb at a side ofthe opposed substrate is larger than the top width wt at a side of thetransparent substrate, it is possible to decrease a portion of thepartition wall to which the transparent substrate is contacted and toincrease a display area. In addition, when the particles are filled inthe image display elements each surrounded by the partition wall, it ispossible to decrease the particles remained on the head portion of thepartition wall and to achieve the simple handling of the particlesduring the manufacturing.

In the first embodiment of the fifth aspect of the invention, it ispreferred that a ratio wt/wb between the bottom width wb at a side ofthe opposed substrate and the top width wt at a side of the transparentsubstrate is not greater than 0.5. Moreover, it is preferred that anaverage particle diameter of the particles is 0.1-50 μm. Further, it ispreferred that the difference of a surface charge density in an absolutevalue between two groups of the particles measured by using the samekind of carrier in accordance with a blow-off method is 5-150 μC/m².Furthermore, it is preferred that the particles are particles in whichthe maximum surface potential, in the case that the surface of particlesis charged by a generation of Corona discharge caused by applying avoltage of 8 KV to a Corona discharge device deployed at a distance of 1mm from the surface of the particles, is greater than 300 V at 0.3second after the Corona discharge. Moreover, it is preferred that acolor of the particles is white or black. In each preferred case, it ispossible to obtain the image display device according to the inventionmore preferably.

A second embodiment of a fifth aspect of the invention has for itsobject to eliminate the drawbacks mentioned above and to provide animage display device having rapid response, simple construction,inexpensive cost and excellent stability, which can further achieve alarger display area and a simple handling of the liquid powders duringthe manufacturing.

According to the second embodiment of the fifth aspect of the invention,an image display device which comprises an image display panel, in whichliquid powders, which indicate a high fluidity in an aerosol state suchhat solid-like substances are suspended in a gas stably as dispersoid,are sealed between opposed two substrates, at least one of twosubstrates being transparent, and, in which the liquid powders, to whichan electrostatic field produced by a pair of electrodes having differentpotentials is applied, are made to move so as to display an image, ischaracterized in that one or more image display elements are formed byusing a partition wall and the partition wall has such a shape that abottom width wb at a side of an opposed substrate is larger than a topwidth wt at a side of a transparent substrate.

In the second embodiment of the fifth aspect of the invention, since thepartition wall has such a shape that the bottom width wb at a side ofthe opposed substrate is larger than the top width wt at a side of thetransparent substrate, it is possible to decrease a portion of thepartition wall to which the transparent substrate is contacted and toincrease a display area. In addition, when the liquid powders are filledin the image display elements each surrounded by the partition wall, itis possible to decrease the liquid powders remained on the head portionof the partition wall and to achieve the simple handling of the liquidpowders during the manufacturing.

In the second embodiment of the fifth aspect of the invention, it ispreferred that a ratio wt/wb between the bottom width wb at a side ofthe opposed substrate and the top width wt at a side of the transparentsubstrate is not greater than 0.5. Moreover, it is preferred that anapparent volume in a maximum floating state of the liquid powders is twotimes or more than that in none floating state. Further, it is preferredthat a time change of the apparent volume of the liquid powderssatisfies the following formula:V ₁₀ /V ₅>0.8;here, V₅ indicates the apparent volume (cm³) of the liquid powders after5 minutes from the maximum floating state; and V₁₀ indicates theapparent volume (cm³) of the liquid powders after 10 minutes from themaximum floating state. Furthermore, it is preferred that an averageparticle diameter d(0.5) of the liquid powders is 0.1-20 μm. In eachpreferred case, it is possible to obtain the image display deviceaccording to the invention more preferably.

A first embodiment of a sixth aspect of the invention has for its objectto eliminate the drawbacks mentioned above and to provide a method ofmanufacturing an image display having rapid response, simpleconstruction, inexpensive cost and excellent stability, which canmaintain a larger connection strength between a partition wall and asubstrate and prevent a leakage of particles.

According to the first embodiment of the sixth aspect of the invention,a method of manufacturing an image display device which comprises animage display panel, in which two or more groups of particles havingdifferent colors and different characteristics are sealed betweenopposed two substrates, at least one of two substrates beingtransparent, in which the particles, to which an electrostatic fieldproduced by two groups of electrodes having different potentials isapplied, are made to move so as to display an image, and, in which oneor more image display elements are formed by using a partition wall, ischaracterized in that the improvement comprises the steps of: formingthe partition wall on one or both of a transparent substrate and anopposed substrate; arranging an adhesive at a tip of the partition wall;and connecting the partition wall and the other substrate or bothpartition walls through the adhesive.

In the first embodiment of the sixth aspect of the invention, since theimprovement comprises the steps of: forming the partition wall on one orboth of a transparent substrate and an opposed substrate; arranging anadhesive at a tip of the partition wall; and connecting the partitionwall and the other substrate or both partition walls through theadhesive, it is possible to achieve a strong connection between thepartition wall and the substrate or a strong connection between thesubstrates and to prevent a leakage of the particles almost completely.

In the first embodiment of the sixth aspect of the invention, it ispreferred that an average particle diameter of the particles is 0.1-50μm. Moreover, it is preferred that the difference of a surface chargedensity in an absolute value between two groups of the particlesmeasured by using the same kind of carrier in accordance with a blow-offmethod is 5-150 μC/m². Further, it is preferred that the particles areparticles in which the maximum surface potential, in the case that thesurface of particles is charged by a generation of Corona dischargecaused by applying a voltage of 8 KV to a Corona discharge devicedeployed at a distance of 1 mm from the surface of the particles, isgreater than 300 V at 0.3 second after the Corona discharge.Furthermore, it is preferred that a color of the particles is white orblack. In each preferred case, it is possible to obtain the method ofmanufacturing the image display device according to the invention morepreferably.

Moreover, an image display device according to the first embodiment ofthe sixth aspect of the invention, an image display device ischaracterized in that the improvement is manufactured in accordance withthe method of manufacturing the image display device mentioned above.

A second embodiment of a sixth aspect of the invention has for itsobject to eliminate the drawbacks mentioned above and to provide amethod of manufacturing an image display having rapid response, simpleconstruction, inexpensive cost and excellent stability, which canmaintain a larger connection strength between a partition wall and asubstrate and prevent a leakage of liquid powders.

According to the second embodiment of the sixth aspect of the invention,a method of manufacturing an image display device which comprises animage display panel, in which liquid powders, which indicate a highfluidity in an aerosol state such that solid-like substances aresuspended in a gas stably as dispersoid, are sealed between opposed twosubstances, at least one of two substrates being transparent, in whichthe liquid powders, to which an electro-static field produced by a pairof electrodes having different potentials is applied are made to move soas to display an image, and, in which one or more image display elementsare formed by using a partition wall, is characterized in that theimprovement comprises the steps of: forming the partition wall on one orboth of a transparent substrate and an opposed substrate; arranging anadhesive at a tip of the partition wall; and connecting the partitionwall and the other substrate or both partition walls through theadhesive.

In the second embodiment of the sixth aspect of the invention, since theimprovement comprises the steps of: forming the partition wall on one orboth of a transparent substrate and an opposed substrate; arranging anadhesive at a tip of the partition wall; and connecting the partitionwall and the other substrate or both partition walls through theadhesive, it is possible to achieve a strong connection between thepartition wall and the substrate or a strong connection between thesubstrates and to prevent a leakage of the liquid powders almostcompletely.

In the second embodiment of the sixth aspect of the invention, it ispreferred that an apparent volume in a maximum floating state of theliquid powders is two times or more than that in none floating state.Moreover, it is preferred that a time change of the apparent volume ofthe liquid powders satisfies the following formula:V ₁₀ /V ₅>0.8;here, V₅ indicates the apparent volume (cm³) of the liquid powders after5 minutes from the maximum floating state; and V₁₀ indicates theapparent volume (cm³) of the liquid powders after 10 minutes from themaximum floating state. Further, it is preferred that an averageparticle diameter d(0.5) of the liquid powders is 0.1-20 μm. In eachpreferred case, it is possible to obtain the method of manufacturing theimage display device according to the invention more preferably.

Moreover, an image display device according to the second embodiment ofthe sixth aspect of the invention, an image display device ischaracterized in that the improvement is manufactured in accordance withthe method of manufacturing the image display device mentioned above.

In the present invention, a term “liquid powder” means an inter-mediatematerial having both of liquid properties and particle properties andexhibiting a self-fluidity without utilizing gas force and liquid force.Preferably, it is a material having an excellent fluidity such thatthere is no repose angle defining a fluidity of powder. For example, aliquid crystal is defined as an intermediate phase between a liquid anda solid, and has a fluidity showing a liquid characteristic and ananisotropy (optical property) showing a solid characteristic (HeibonshaLtd.: encyclopedia). On the other hand, a definition of the particle isa material having a finite mass if it is vanishingly small and receivesan attraction of gravity (Maruzen Co., Ltd.: physics subject-book).Here, even in the particles, there are special states such as gas-solidfluidized body and liquid-solid fluidized body. If a gas is flown from abottom plate to the particles, an upper force is acted with respect tothe particles in response to a gas speed. In this case, the gas-solidfluidized body means a state that is easily fluidized when the upperforce is balanced with the gravity. In the same manner, the liquid-solidfluidized body means a state that is fluidized by a liquid. (HeibonshaLtd.: encyclopedia) In the present invention, it is found that theintermediate material having both of fluid properties and solidproperties and exhibiting a self-fluidity without utilizing gas forceand liquid force can be produced specifically, and this is defined asthe liquid powder.

That is, as is the same as the definition of the liquid crystal(inter-mediate phase between a liquid and a solid), the liquid powderaccording to the invention is a material showing the intermediate statehaving both of liquid properties and particle properties, which isextremely difficult to receive an influence of the gravity showing theparticle properties mentioned above and indicates a high fluidity. Sucha material can be obtained in an aerosol state i.e. in a dispersionsystem wherein a solid-like or a liquid-like material is floating in arelatively stable manner as a dispersant in a gas, and thus, in theimage display device according to the invention, a solid material isused as a dispersant.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic view explaining one embodiment of a display methodof an image display panel in an image display device according to theinvention.

FIG. 2 is a schematic view explaining another embodiment of the displaymethod of the image display panel in the image display device accordingto the invention.

FIG. 3 is a schematic view explaining one embodiment of a structure ofthe image display panel in the image display device according to theinvention.

FIG. 4 is a schematic view explaining still another embodiment of thedisplay method in the image display device according to the invention.

FIG. 5 is a schematic view explaining still another embodiment of thedisplay method in the image display device according to the invention.

FIG. 6 is a schematic view explaining another embodiment of thestructure in the image display device according to the invention.

FIGS. 7 a-7 c are schematic views respectively showing one embodiment inan image display element of the image display panel constituting theimage display device according to the invention and its display drivingtheory.

FIG. 8 is a schematic view illustrating another embodiment of thestructure in the image display element of the image display panelconstituting the image display device according to the invention.

FIG. 9 is a schematic view depicting one embodiment of a shape ofpartition walls in the image display device according to the invention.

FIG. 10 is a schematic view showing a method of measuring a surfacepotential of a particle used in the image display device according tothe invention.

FIG. 11 is a graph explaining a relation between an applied voltage anda reflection density in an estimation of a display function of the imagedisplay device according to the invention.

FIG. 12 is a graph illustrating an optical performance of ananti-reflection layer formed in the embodiment.

FIGS. 13 a-13 c are schematic views respectively depicting a step ofconnecting the substrates in the image display device according to theinvention.

FIGS. 14 a-14 c are schematic views respectively showing anotherembodiment of the image display element in the image display deviceaccording to the invention.

FIGS. 15 a and 15 b are longitudinal cross sectional views respectivelyillustrating one embodiment of a shape of the partition wall used in theimage display device according to the invention.

FIG. 16 is a schematic view explaining a case such that a displayelectrode is arranged on a transparent substrate and an opposedelectrode is arranged on an opposed substrate, as another embodiment ofthe display element in the image display device according to theinvention.

FIG. 17 is a schematic view explaining another method of forming thepartition wall in the image display device according to the invention.

FIG. 18 is a schematic view explaining another method of forming thepartition wall in the image display device according to the invention.

FIG. 19 is a schematic view explaining one method of forming thepartition wall inn the image display device according to the invention.

FIG. 20 is a schematic view showing one method of manufacturing thepartition wall constituting the image display element in a method ofmanufacturing the image display device according to the invention.

FIG. 22 is a schematic view explaining one method of forming thepartition wall according to the invention.

FIG. 23 is a schematic view explaining another method of forming thepartition wall according to the invention.

FIG. 24 is a schematic view explaining one method of forming thepartition wall according to a comparative example.

BEST MODE FOR CARRYING OUT THE INVENTION

At first, various constructions of an image display device according tothe invention will be explained. In the following explanations, itshould be noted that there are a first embodiment and a secondembodiment in first aspect to sixth aspect of the invention respectivelyand that the first embodiment shows an example of particles and thesecond embodiment illustrates an example of liquid powders.

In the first embodiment wherein the particles are utilized in an imagedisplay panel of the image display device according to the invention,one or more groups of particles 5, 6 are sealed between a transparentsubstrate 1 and an opposed substrate 2, and an electrostatic field isapplied from two groups of electrodes 3, 4 having a different potentialto the particles 5, 6 so as to move the particles 5, 6 so that an imageis displayed.

As to forces applied to the particles, there are an attraction forcebetween the particles due to Coulomb' force, an imaging force withrespect to the electrode panel, an intermolecular force, a liquidbridging force and a gravity.

The image display can be applied to a display method wherein two or morekinds of particles having different colors are moved in a verticaldirection with respect to the substrate as shown in FIG. 1 and also to adisplay method wherein one kind of particles having one color are movedin a parallel direction with respect to the substrate as shown in FIG.2. From the viewpoint of stability, it is preferred that the imagedisplay device of this embodiment is applied to the former displaymethod.

FIG. 3 is a schematic view explaining a construction of the imagedisplay device according to the first embodiment in respective aspectsof the invention. It is constructed by opposed substrates 1, 2,particles 5, 6 and a partition wall 7 according to need.

Also in the second embodiment wherein the liquid powders for the imagedisplay are utilized in the image display device according to theinvention, as is the same as the first embodiment utilizing theparticles, the image display can be applied to a display method whereintwo or more kinds of liquid powders having different colors are moved ina vertical direction with respect to the substrate as shown in FIG. 4and also to a display method wherein one kind of liquid powders havingone color are moved in a parallel direction with respect to thesubstrate as shown in FIG. 5. From the viewpoint of stability, it ispreferred that the image display device of this embodiment is applied tothe former display method.

FIG. 6 is a schematic view explaining a construction of the imagedisplay device according to the second embodiment in respective aspectsof the invention. It is constructed by opposed substrates 1, 2, liquidpowders 5, 6 arranged between the substrates and a partition wall 7according to need.

FIGS. 7 a to 7 c are schematic views respectively showing anotherembodiments of the image display element of the image display panel usedfor the image display device according to the invention and its displaydriving method. In the embodiments shown in FIGS. 7 a to 7 c, numeral 1is a transparent substrate, numeral 2 is an opposed substrate, numeral 3is a display electrode, numeral 4 is an opposed electrode, numeral 5 isa negatively chargeable particle, numeral 6 is a positively chargeableparticle, numeral 7 is a partition wall and numeral 8 is an insulationmember.

FIG. 7 a shows a state such that the negatively chargeable particles 5and the positively chargeable particles 6 are arranged between opposedsubstrates (transparent substrate 1 and opposed substrate 2). Under sucha state, when a voltage is applied in such a manner that a side of thedisplay electrode 3 becomes low potential and a side of the opposedelectrode 4 becomes high potential, as shown in FIG. 7 b, the positivelychargeable particles 6 move to the side of the display electrode 3 andthe negatively chargeable particles 5 move to the side of the opposedelectrode 4 by means of Coulomb's force. In this case, a display faceviewed from a side of the transparent substrate 1 looks like a color ofthe positively chargeable particles 6. Next, when a voltage is appliedin such a manner that the side of the display electrode 3 becomes highpotential and the side of the opposed electrode 4 becomes low potentialby reversing potentials, as shown in FIG. 7 c, the negatively chargeableparticles 5 move to the side of the display electrode 3 and thepositively chargeable particles 6 move to the side of the opposedelectrode 4 by means of Coulomb's force. In this case, the display faceviewed from the side of the transparent substrate 1 looks like a colorof the negatively chargeable particles 5.

The display states shown in FIGS. 7 b and 7 c are repeatedly changeableonly by reversing the potentials of a power source, and thus it ispossible to change colors on the display face reversibly by reversingthe potentials of the power source as mentioned above. The colors of theparticles can be arbitrarily selected. For example, when the negativelychargeable particles 5 are white color and the positively chargeableparticles 6 are black color, or, when the negatively chargeableparticles 5 are black color and the positively chargeable particles 5are white color, a reversible image display between white color andblack color can be performed. In this method, since the particles areonce adhered to the electrode by means of an imaging force, a displayimage can be maintained for a long time after a voltage apply isstopped, thereby showing an excellent memory property.

In the present invention, since the chargeable particles fly and move inthe gas, the response rate of the image display is extremely fast andthe response rate of shorter than 1 msec may be possible. Moreover, itis not necessary to use an orientation film and a polarizing plate asthe liquid crystal display, and thus it is possible to make thestructure simple and to realize the image display device having a largedisplay area at a lower cost. In addition, it is stable with respect toa temperature variation and can be used in a wide temperature range froma low temperature to a high temperature. Further, it is not affected byan angle of visual field and has a high reflection coefficient.Therefore, it is easily viewable and has low electric power consumption.Furthermore, it has an excellent memory property and thus it is notnecessary to use an electric power when the image is to be maintained.

FIG. 8 is a schematic view showing still another embodiment of the imagedisplay element of the image display panel according to the invention.In the embodiment shown in FIG. 8, irrespective of the embodiments shownin FIGS. 7 a to 7 c, the display electrode 3 is arranged to thetransparent substrate 1 and the opposed electrode 4 is arranged to theopposed substrate 2. In the embodiment shown in FIG. 8, it is necessaryto use a transparent electrode as the display electrode 3. On the otherhand, in the embodiments shown in FIGS. 7 a to 7 c, since an opaqueelectrode can be used as the display electrode 3, it is possible to usea metal electrode having an inexpensive cost and a low resistance suchas copper, aluminum and so on, and thus it is preferred.

It should be noted that, in the embodiments shown in FIGS. 7 a-7 c and8, the explanation is made to a case utilizing the particles, but thesame explanation can be applied to a case utilizing the liquid powders.

Hereinafter, the substrate, the electrode and the partition wall amongmembers constituting the image display device according to the inventionwill be explained.

With respect to the substrate, at least one of the substrates is thetransparent substrate 1 through which a color of the particles can beobserved from outside of the device, and it is preferred to use amaterial having a high transmission factor of visible light and anexcellent heat resistance. The opposed substrate 2 may be transparent ormay be opaque. Whether a flexibility of the substrate is necessary ornot is suitably selected in accordance with its use. For example, it ispreferred to use a material having flexibility for the use of electronicpaper and so on, and it is preferred to use a material having noflexibility for the use of a display of portable device such as mobilephone, PDA, laptop computer and so on. Examples of the substratematerial include polymer sheets such as polyethylene terephthalate,polymer sulfone, polyethylene, polycarbonate, polyimide or acryl andinorganic sheets such as glass, quartz or so. The thickness of thesubstrate is preferably 2 to 5000 μm, more preferably 5 to 1000 μm. Whenthe thickness is too thin, it becomes difficult to maintain strength anddistance uniformity between the substrates, and when the thickness istoo thick, vividness and contrast as a display capability degrade, andin particular, flexibility in the case of using for an electronic paperdeteriorates.

In the image display device according to the invention, an electrode maybe arranged on the substrate according to need.

In the case of arranging no electrode on the substrate, the particles orthe liquid powder charged in a predetermined potential and having acolor is pulled in or rebounds with respect to the substrate by means ofan electric field generated by applying an electrostatic latent image onan outer surface of the substrate. Then, the particles or the liquidpowder aligned in accordance with the electrostatic latent image isobserved from outside of the display device through the transparentsubstrate. In this case, the electrostatic latent image mentioned abovecan be generated for example by a method wherein an electrostatic latentimage generated in a known electrophotography system using anelectrophotography photo-conductor is transferred and formed on thesubstrate of the image display device according to the invention, or, bya method wherein an electrostatic latent image is directly formed on thesubstrate by an ion flow.

In the case of arranging an electrode on the substrate, the particles orthe liquid powder charged in a predetermined characteristic and having acolor is pulled in or rebounds with respect to the substrate by means ofan electric field generated on respective electrodes formed on thesubstrate by applying an outer voltage thereto. Then, the particles orthe liquid powder aligned in accordance with the electrostatic latentimage is observed from outside of the display device through thetransparent substrate.

In this case, the electrode may be formed of electroconductive materialswhich are transparent and having patter formation capability.Additionally, the thickness of the electrode may be suitable unless theelectro-conductivity is absent or any hindrance exists in opticaltransparency, and it is preferable to be 3 to 1000 nm, more preferableto be 5 to 400 nm. In this case, the applied outer voltage may besuperimposed with a direct current or an alternate current.

In the image display device according to the invention, it is preferredto arrange the partition wall 7 shown in respective figures at aperiphery of respective display elements. The partition wall may bearranged only in a parallel direction. In this manner, it is possible toprevent an unnecessary movement of the particles in a direction parallelto the substrate, to help a repeatedly endurance property and a memorymaintaining property and to improve a strength of the image displaypanel by making a distance between the substrates even and strong. Thatis, in the image display device according to the invention, in order toprevent an unnecessary movement of the liquid powder in a directionparallel to the substrate, it is preferred to form a partition wallbridging the opposed substrates and to construct the display portion bya plurality of display cells.

A shape of the partition wall is suitably designed in accordance with asize of the particles or the liquid powder to be used for the displayand is not restricted. However, it is preferred to set a width of thepartition wall to 1-100 μm more preferably 2-50 μm and to set a heightof the partition wall to 10-5000 μm more preferably 10-500 μm.

Moreover, as a method of forming the partition wall, use may be made ofa double rib method wherein ribs are formed on the opposed substratesrespectively and they are connected with each other and a single ribmethod wherein a rib is formed on one of the opposed substrates only. Inthe image display device according to the invention, in order to preventa connection deviation, it is preferred to use the single rib method forthe partition wall formation.

The display cell formed by the partition walls each made of rib has asquare shape, a triangular shape, a line shape, a circular shape, ahexagon shape (honeycomb structure) as shown in FIG. 9 viewed from aplane surface of the substrate.

It is better to minimize a portion (area of frame portion of the displaycell) corresponding to a cross section of the partition walls viewedfrom the display side. In this case, it is possible to improve aclearness of the image display. The formation method of the partitionwall 7 is not particularly restricted, however, a screen printing methodwherein pastes are overlapped by coating repeatedly on a predeterminedposition by screen plate; a sandblast method wherein partition materialsare painted with a desired thickness entirely over the substrate andthen after coating resist pattern on the partition materials which iswanted to be left as a partition, jetting abrasive to cut and removepartition materials aside from the partition part; lift-off method(additive method) wherein a resist pattern is formed on the substrateusing photosensitive polymer, and then after burying paste into a resistrecess, removing the resist; photo-sensitive paste method wherein thephotosensitive resin composition containing the partition materials isapplied over the substrate and then obtaining a desired pattern byexposure & developing; and mold formation method wherein pastecontaining the partition materials is applied over the substrate andthen forming a partition by compression bonding & pressure forming thedies having rugged structure; and so on are adopted. Further, modifyingthe mold formation method, relief embossing method wherein a reliefpattern provided by a photosensitive polymer composition is used as amold is also adopted.

Then, the particles used in the first embodiment of respective aspectsof the invention will be explained.

As the particles used in the first embodiment of the image displaydevice according to the invention, although any of colored particlesnegatively or positively chargeable having capability of flying andmoving by Coulomb's force are employable, spherical particles with lightspecific gravity are particularly preferable. The average particlediameter is preferable to be 0.1 to 50 μm, particularly to be 1 to 30μm. When the particle diameter is less than this range, charge densityof the particles will be so large that an imaging force to an electrodeand a substrate becomes too strong; resulting in poor following abilityat the inversion of its electric field, although the memorycharacteristic is favorable. On the contrary, when the particle diameterexceeds the range, the following ability is favorable, however, thememory characteristic will degrade.

Although the method for charging the particles negatively or positivelyis not particularly limited, a corona discharge method, an electrodeinjection-charge method, a friction charge method and so on areemployable.

A charge amount of the particles is depend on the measuring condition,i.e., the charge amount of the particles in the image display device isdepend on its initial charge amount, a contact with the substrate, acontact between the particles having different kinds, and a chargedecrease due to a lapse of time. Particularly, it is understood that amain factor is “the contact between the particles having differentkinds”, i.e., a saturated value of a charge behavior due to the contactbetween two particles. Therefore, it is important to know a differenceof the charge characteristics between two particles on the chargeamount, i.e., to know a difference of a work function. However, it isdifficult to know these differences by an easy measurement.

The inventors investigated theses differences and find that it ispossible to estimate these differences relatively by using same carriersand measuring the charge amount of respective particles by means of ablow-off method. Moreover, if the measuring results are defined by asurface charge density, it is possible to perform an estimation of thecharge amount of the particles as a suitable method for the imagedisplay device.

The measuring method will be explained later in detail. By performingthe blow-off method, it is possible to contact the particles and thecarrier particles sufficiently and to measure the charge amount per unitweight of respective particles by measuring its saturated charge amount.Then, it is possible to calculate the surface charge density ofrespective particles by obtaining a particle diameter and a specificgravity of respective particles separately.

In the image display device, since a particle diameter of the particlesto be used is small and an affection of gravity is too small to neglectits affection, the specific gravity is not affected to the movement ofthe particles. However, on the charge amount of the particles, if theparticles have a same particle diameter and a same average charge amountper unit weight, the maintained charge amounts are different by twotimes in the case that the specific gravities of the particles aredifferent by two times. Therefore, it is understood that it is preferredto estimate the charge characteristics of the particles used in theimage display device by the surface charge density (unit: μC/m²) whichis irrelevant to the specific gravity of the particles.

Then, when the difference of this surface charge density is sufficientlylarge between the particles, two groups of the particles maintain thecharge amounts of different characteristics by contacting them with eachpother and a function of the movement by an electrostatic field is alsomaintained.

Here, it is necessary to obtain some degree of difference on the surfacecharge density so as to differentiate the charge characteristics of thetwo particles, but it is not always necessary to make the difference onthe surface charge density larger. In the image display device utilizingthe particle movement, when a particle diameter of the particles islarge, the main factor for determining a fly/move electrostatic field(voltage) of the particles is an electric imaging force. Therefore, inorder to move the particles by a low electrostatic field (voltage), itis preferred to make the charge amount low. Moreover, when a particlediameter of the particles is small, the main factor for determining thefly/move electrostatic field (voltage) is a non-electric force such asan intermolecular force, a liquid bridging force and so on. Therefore,in order to move the particles by a low electrostatic field (voltage),it is preferred to make the charge amount high. However, since thesesphenomena are largely depend on surface properties (material, shape) ofthe particles, it is not possible to define only by the particlediameter and the charge amount.

The inventors find that, in the particles having an average particlediameter of 0.1-50 μm, when the absolute value of the difference betweenthe surface charge densities of two groups of particles, which aremeasured by the blow-off method using the same kind of particles, is5-150 μC/m², it is possible to obtain the particles usable for the imagedisplay device.

Measuring theory and method of the blow-off method are as follows. Inthe blow-off method, a mixture of the particles and the carriers areplaced into a cylindrical container with nets at both ends, andhigh-pressure gas is blown from the one end to separate the particlesand the carriers, and then only the particles are blown off from themesh of the net. In this occasion, charge amount of reverse blownpolarity remains on the carriers with the same charge amount of theparticles carried away out of the container. Then, all of electric fluxby this electric charge are collected to Faraday cage, and are chargedacross a capacitor with this amount. Accordingly, the charge amount ofthe particles is determined as Q=CV (C: capacity, V: voltage across bothends of the capacitor) by measuring potential of both ends of thecapacitor.

In the invention, as a blow-off powder charge amount measuringinstrument, TB-200 produced by Toshiba Chemical Co., Ltd. was used, andF963-2535 available from Powder TEC Co., Ltd. was employed as the samekind of carriers. Then, the charge density per unit surface area (unit:μC/m²) was measured.

Because it is necessary for the particles to hold the charged electriccharge, insulating particles with the volume specific resistance of1×10¹⁰ Ω·cm or greater are preferable, and in particular, insulatingparticles with the volume specific resistance of 1×10¹² Ω·cm or greaterare more preferable.

Further, the particles with slow charge attenuation property evaluatedby the measuring method below are more preferable. That is, theparticles are made into a film having a thickness of 5-100 μm by meansof a press method, a heating/melting method, a casting method and so on,and the voltage of 8 kV is applied to a Corona generator disposed with adistance of 1 mm to the film surface so as to generate Corona discharge,which charges the film surface. Then, the change of the surfacepotential is measured to determine the suitability. In this occasion, itis preferable to select the material whose maximum surface potentialwill be 300 V or greater after 0.3 seconds, more preferable to selectthe material whose maximum surface potential will be 400 V or greaterafter 0.3 second as the material for composing the particles.

Additionally, the foregoing surface potential is measured by means of aninstrument (CRT2000 produced by QEA Inc.) as shown in FIG. 10. In thisinstrument both end portions of a roll shaft being held with chuck 21,compact scorotron discharger 22 and surface potential meter 23 arespaced with predetermined interval to form a measurement unit. Facedlydeploying the measurement unit with a distance of 1 mm from the surfaceof the particles, and by moving the measurement unit from one endportion of the roll shaft to the other end portion with an uniformspeed, with the state that the roll shaft remains stopping and whilegiving surface charge, a method of measuring its surface potential ispreferably adopted. Moreover, measurement environment should be settledat the temperature of 25±3° C. and the humidity of 55±5% RH.

If the particles satisfy electrostatic property and so on, the particlesmay be formed by any materials. For example, it is formed by resin,charge control agent, coloring agent, inorganic additive and so on, or,by coloring agent and so on only. Typical examples of the resin includeurethane resin, urea resin, acrylic resin, polyester resin, acrylurethane resin, acryl urethane silicone resin, acryl urethanefluorocarbon polymers, acryl fluorocarbon polymers, silicone resin,acryl silicone resin, epoxy resin, polystyrene resin, styrene acrylicresin, polyolefin resin, butyral resin, vinylidene chloride resin,melamine resin, phenolic resin, fluorocarbon polymers, polycarbonateresin, polysulfon resin, polyether resin, and polyamide resin. For thepurpose of controlling the attaching force with the substrate, acrylurethane resin, acryl silicone resin, acryl fluorocarbon polymers, acrylurethane silicone resin, acryl urethane fluorocarbon polymers,fluorocarbon polymers, silicone resin are particularly preferable. Twokinds or more of these may be mixed and used.

Examples of the electric charge control agent include, but notparticularly specified to, negative charge control agent such assalicylic acid metal complex, metal containing azo dye, oil-soluble dyeof metal-containing (containing a metal ion or a metal atom), the fourthgrade ammonium salt-based compound, calixarene compound,boron-containing compound (benzyl acid boron complex), andnitroimidazole derivative. Examples of the positive charge control agentinclude nigrosine dye, triphenylmethane compound, the fourth gradeammonium salt compound, polyamine resin, imidazole derivatives, etc.Additionally, metal oxides such as ultra-fine particles of silica,ultra-fine particles of titanium oxide, ultra-fine particles of alumina,and so on; nitrogen-containing circular compound such as pyridine, andso on, and these derivates or salts; and resins containing variousorganic pigments, fluorine, chlorine, nitrogen, etc. can be employed asthe electric charge control agent.

As for a coloring agent, various kinds of organic or inorganic pigmentsor dye as will be described below are employable.

Examples of black pigments include carbon black, copper oxide, manganesedioxide, aniline black, and activate carbon.

Examples of yellow pigments include chrome yellow, zinc chromate,cadmium yellow, yellow iron oxide, mineral first yellow, nickel titaniumyellow, navel orange yellow, naphthol yellow S, hanzayellow G,hanzayellow 10G, benzidine yellow G, benzidine yellow GR, quinolineyellow lake, permanent yellow NCG, and tartrazinelake.

Examples of orange pigments include red chrome yellow, molybdenumorange, permanent orange GTR, pyrazolone orange, Balkan orange, indusrenbrilliant orange RK, benzidine orange G, and Indusren brilliant orangeGK.

Examples of red pigments include red oxide, cadmium red, diachylon,mercury sulfide, cadmium, permanent red 4R, lithol red, pyrazolone red,watching red, calcium salt, lake red D, brilliant carmine 6B, eosinlake, rhodamine lake B, alizarin lake, and brilliant carmine 3B.

Examples of purple pigments include manganese purple, first violet B,and methyl violet lake.

Examples of blue pigments include Berlin blue, cobalt blue, alkali bluelake, Victoria blue lake, phthalocyanine blue, metal-free phthalocyanineblue, partially chlorinated phthalocyanine blue, first sky blue, andIndusren blue BC.

Examples of green pigments include chrome green, chromium oxide, pigmentgreen B, Malachite green lake, and final yellow green G.

Further, examples of white pigments include zinc white, titanium oxide,antimony white, and zinc sulphide.

Examples of extenders include baryta powder, barium carbonate, clay,silica, white carbon, talc, and alumina white.

Furthermore, there are Nigrosine, Methylene Blue, rose bengal, quinolineyellow, and ultramarine blue as various dyes such as basic dye, acidicdye, dispersion dye, direct dye, etc.

These coloring agents may be used alone or in combination of two or morekinds thereof.

Particularly, carbon black is preferable as the black coloring agent,and titanium oxide is preferable as the white coloring agent.

Although the manufacturing method of the particles is not specificallyrestricted, mixing/grinding method or polymerization method forproducing toner of electrophotography is, for example, similarlyemployable. Further the method of coating resin or charge control agentand so on over the surface of powders such as inorganic or organicpigments is also employable.

The distance between the transparent substrate 1 and the opposedsubstrate 2 is suitably adjusted in a manner where the particles canmove and maintain the contrast of image display; however, it is adjustedusually within 10 to 5000 μm, preferably within 30 to 500 μm.

The particle filling amount (volume occupying rate) of the particlesexisting in the space between the faced substrates is preferable to be10 to 80%, more preferable to be 10 to 70%.

In the image display panel used in the image display device according tothe invention, plural of the foregoing display elements are dispose in amatrix form, and images can be displayed. In the case of monochromedisplay, one display element makes one pixel. In the case of full colordisplay, three kinds of display elements, i.e., one group of displayelements each having color plate of R (red), G (green) and B (blue)respectively and each having particles of black composes a set ofdisposed elements preferably resulting in the reversible image displaypanel having the sets of the elements.

Then, the liquid powders utilized in the second embodiment of respectiveaspects of the invention will be explained.

As mentioned above, the liquid powder is an intermediate material havingboth of liquid properties and particle properties and exhibiting aself-fluidity without utilizing gas force and liquid force. The liquidpowder becomes particularly an aerosol state, and thus, in the imagedisplay device according to the invention, it is utilized under such acondition that a solid material is floated in a gas as a dispersant in arelatively stable manner.

As the aerosol state, it is preferred that an apparent volume in amaximum floating state is two times or more than that in none floatingstate, more preferably 2.5 times or more than that in none floatingstate, and most preferably three times or more than that in nonefloating state. In this case, an upper limit is not defined, but it ispreferred that an apparent volume is 12 times or smaller than that innone floating state.

If the apparent volume in the maximum floating state is smaller than twotimes, a display controlling becomes difficult. On the other hand, ifthe apparent volume in the maximum floating state is larger than 12times, a handling inconvenience during a liquid powder filling operationinto the device such as a particle over-scattering occurs. That is, itis measured by filling the liquid powder in a transparent closed vesselthrough which the liquid powder is seen; vibrating or dropping thevessel itself to obtain a maximum floating state; and measuring anapparent volume at that time from outside of the vessel. Specifically,the liquid powder having a volume ⅕ of the vessel is filled as theliquid powder in a vessel with a polypropylene cap having a diameter(inner diameter) of 6 cm and a height of 10 cm (product name I-boy®produced by As-one Co., Ltd.), the vessel is set in the vibrator, and avibration wherein a distance of 6 cm is repeated at a speed of 3reciprocating/sec. is performed for 3 hours. Then, the apparent volumein the maximum floating state is obtained from an apparent volume justafter a vibration stop.

Moreover, in the image display device according to the invention, it ispreferred that a time change of the apparent volume of the liquid powdersatisfies the floating formula:V ₁₀ /V ₅>0.8;here, V₅ indicates the apparent volume (cm³) of the liquid powder after5 minutes from the maximum floating state; and V₁₀ indicates theapparent volume (cm³) of the liquid powder after 10 minutes from themaximum floating state. In this case, in the image display deviceaccording to the invention, it is preferred to set the time changeV₁₀/V₅ of the apparent volume of the liquid powder to larger than 0.85,more preferably larger than 0.9, most preferably larger than 0.95. Ifthe time change V₁₀/V₅ is not larger than 0.8, the liquid powder issubstantially equal to normal particles, and thus it is not possible tomaintain a high speed response and durability according to theinvention.

Moreover, it is preferred that the average particle diameter d(0.5) ofthe particle materials constituting the liquid powder is 0.1-20 μm, morepreferably 0.5-15 μm, most preferably 0.9-8 μm. If the average particlediameter d(0.5) is less than 0.1 μm, a display controlling becomesdifficult. On the other hand, if the average particle diameter d(0.5) islarger than 20 μm, a display is possible, but opacifying power isdecreased and thus a thin shape device is difficult. Here, the averageparticle diameter d(0.5) of the particle materials constituting theliquid powder is equal to d(0.5) in the following particle diameterdistribution Span.

It is preferred that particle diameter distribution Span of the particlematerial constituting the liquid powder, which is defined by thefollowing formula, is not more than 5 preferably not more than 3:Span=(d(0.9)−d(0.1))/d(0.5);here, d(0.5) means a value of the particle diameter expressed by μmwherein an amount of the particle material constituting the liquidpowder having the particle diameter larger than this value is 50% and anamount of the particle material constituting the liquid powder havingthe particle diameter expressed by μm wherein an amount of the particlematerial constituting the liquid powder having a particle diametersmaller than this value is 10%, and d(0.9) means a value of the particlediameter expressed by μm wherein an amount of the particle materialconstituting the liquid powder having the particle diameter smaller thanthis value is 90%. If the particle diameter distribution Span of theparticle materials constituting the liquid powder is set to not morethan 5, the particle diameter becomes even and it is possible to performan even liquid powder movement.

Here, the particle diameter distribution and the particle diametermentioned above can be measured by means of a laserdiffraction/scattering method. When a laser light is incident upon theparticles to be measured, a light intensity distribution pattern due toa diffraction/scattering light occurs spatially. This light intensitydistribution pattern corresponds to the particle diameter, and thus itis possible to measure the particle diameter and the particle diameterdistribution. In the present invention, it is defined that the particlediameter and the particle diameter distribution are obtained by a volumestandard distribution. Specifically, the particle diameter and theparticle diameter distribution can be measured by means of a measuringapparatus Mastersizer 2000 (Malvern Instruments Ltd.) wherein theparticles setting in a nitrogen gas flow are calculated by an installedanalysis software (which is based on a volume standard distribution dueto Mie's theory).

The liquid powder may be formed by mixing necessary resin, chargecontrol agent, coloring agent, additive and so on and grinding them, or,by polymerizing from monomer, or, by coating a particle with resin,charge control agent, coloring agent, and additive and so on.Hereinafter, typical examples of resin, charge control agent, coloringagent, additive and so on constituting the liquid powder will beexplained.

Typical examples of the resin include urethane resin, acrylic resin,polyester resin, acryl urethane resin, silicone resin, nylon resin,epoxy resin, styrene resin, butyral resin, vinylidene chloride resin,melamine resin, phenolic resin, fluorocarbon polymers, and it ispossible to combine two or more resins. For the purpose of controllingthe attaching force with the substrate, acryl urethane resin, acrylurethane silicone resin, acryl urethane fluorocarbon polymers, urethaneresin, fluorocarbon polymers.

Examples of the electric charge control agent include, positive chargecontrol agent include the fourth grade ammonium salt compound, nigrosinedye, triphenylmethane compound, imidazole derivatives, and so on, andnegative charge control agent such as metal containing azo dye,salicylic acid metal complex, nitroimidazole derivative and so on.

As for a coloring agent, various kinds of basic or acidic dye may beemployable. Examples include Nigrosine, Methylene Blue, quinolineyellow, rose bengal and do on.

Examples of the inorganic additives include titanium oxide, Chinesewhite, zinc sulfide, antimonial oxide, calcium carbonate, zinc white,talc, silica, calcium silicate, alumina white, cadmium yellow, cadmiumred, cadmium orange, titanium yellow, iron blue, ultramarine blue,cobalt blue, cobalt green, cobalt violet, ferric oxide, carbon black,copper powder, aluminum powder and so on.

However, if the above materials are only mixed or coated with nocontrivance, the liquid powder exhibiting an aerosol state cannot beobtained. The regular method of forming the liquid powder exhibiting anaerosol state is not defined, but the following method is preferablyused.

At first, inorganic fine particles having an average particle size of20-100 nm preferably 20-80 nm are preferably fixed on a surface ofmaterials constituting the liquid powder. Moreover, it is preferred totreat the inorganic fine particles by a silicone oil. Here, as for theinorganic fine particles, use may be made of silicon dioxide (silica),zinc oxide, aluminum oxide, magnesium oxide, cerium oxide, ferric oxide,copper oxide and so on. In this case, a method of fixing the inorganicfine particles is important. For example, use may be made of hybridizer(NARA-KIKAI Industry Co., Ltd.) or mechano-fusion (Hosokawa Micron Co.,Ltd.), and the liquid powders showing an aerosol state are formed undera predetermined condition (for example processing time).

Here, in order to further improve a repeating durability, it iseffective to control a stability of the resin constituting the liquidpowder, especially, a water absorbing rate and a solvent insoluble rate.It is preferred that the water absorbing rate of the resin constitutingthe liquid powder sealed between the substrates is not more than 3 wt %especially not more than 2 wt %. In this case, a measurement of thewater absorbing rate is performed according to ASTM-D570 and a measuringcondition is 23° C. for 24 hours. As for the solvent insoluble rate ofthe liquid powder, it is preferred that a solvent insoluble rate of theliquid powder, which is defined by the following formula, is not lessthan 50% more preferably not less than 70%:solvent insoluble rate (%)=(B/A)×100;(here, A is a weight of the liquid powder before being immersed into thesolvent and B is a weight of resin components after the liquid powder isimmersed into good solvent at 25° C. for 24 hours).

If the solvent insoluble rate is less than 50%, a bleed is generated ona surface of the particle material constituting the liquid powder whenmaintaining for a long time. In this case, it affects an adhesion powerwith the liquid powder and prevent a movement of the liquid powder.Therefore, there is a case such that it affects a durability of theimage display. Here, as a solvent (good solvent) for measuring thesolvent insoluble rate, it is preferred to use fluoroplastic such asmethyl ethyl ketone and so on, polyamide resin such as methanol and soon, acrylic urethane resin such as methyl ethyl ketone, toluene and soon, melamine resin such as acetone, isopropanol and so on, siliconeresin such as toluene and so on.

As for a filling amount of the liquid powder, it is preferred to controlan occupied volume (volume occupied rate) of the liquid powder to 5-85vol %, more preferably 10-65 vol %, most preferably 15-55 vol % of aspace between the opposed substrates. Since the liquid powder exhibitsan aerosol state, it is difficult to use a normal filling method forfilling the liquid powder in the display device. In this case, it ispreferred to use an electrostatic plating apparatus and to adhere theliquid powder to the substrate by force so as to perform an easyhandling. In addition, the liquid powder may be adhered to one of thesubstrates or may be adhered to both of the substrates, and then thesubstrates are connected.

Further, in the present invention, it is important to control a gas in agap surrounding the liquid powder between the substrates, and a suitablegas control contributes an improvement of a display stability.Specifically, it is important to control a humidity of the gap gas tonot more than 60% RH at 25° C., preferably not more than 50% RH, morepreferably not more than 35% RH. The above gap means a gas portionsurrounding the liquid powder obtained by substituting an occupiedportion of the liquid powder 5, 6, an occupied portion of the partitionwall 4 and a seal portion of the device from the space between theopposed substrates 1 and 2 in FIGS. 7 and 8.

A kind of the gap gas is not limited if it has the humidity mentionedabove, but it is preferred to use dry air, dry nitrogen gas, dry heliumgas, dry carbon dioxide gas, dry methane gas and so on. It is necessaryto seal this gas in the device so as to maintain the humidity mentionedabove. For example, it is important to perform the operations of fillingthe liquid powder and assembling the substrate under an atmospherehaving a predetermined humidity and to apply a seal member and a sealmethod for preventing a humidity inclusion from outside of the device.

The image display device according to the invention is applicable to theimage display unit for mobile equipment such as notebook personalcomputers, PDAs, cellular phones and so on; to the electric paper forelectric book, electric newspaper and so on; to the bulletin boards suchas signboards, posters, blackboards and so on; to the rewritable papersubstituted for a paper of copy machine, printer and so on; and to theimage display unit for electric calculator, home electric applicationproducts, auto supplies and so on.

Hereinafter, features of the first aspect to the sixth aspect of theinvention will be explained in sequential order.

AS TO THE FIRST ASPECT OF THE INVENTION

The feature of the image display device according to the first aspect ofthe invention is to use an anisotropic conductive film for providing amember such as an electrode for transmitting a signal, which is appliedto circuits for an image display, to the substrate. As the member exceptthe electrode for transmitting a signal, which is applied to the circuitfor the image display, use is made of the IC chips and so on.

Moreover, use may be made of the anisotropic conductive film formed byscattering conductive particles in a thermosetting adhesive or aphotocuring adhesive.

As the thermosetting adhesive or the photocuring adhesive, it ispreferred to use a polymer including one or more groups of compoundshaving one of glycidyl group, acrylic group and methacrylic group. Forexample, us is made of: ethylene-vinyl acetate copolymer; copolymer ofethylene-vinyl acetate-acrylate monomer and/or methacrylate monomer;copolymer of ethylene-vinyl acetate-maleic acid and/or maleic anhydride;copolymer of ethylene-acrylate monomer and/or methacrylatemonomer-maleic acid and/or maleic anhydride; and ionomer resin wherein ametal ion is coupled between molecules in ethylene-methacrylic acidcopolymer.

The anisotropic conductive film mentioned above can be obtained by:adding organic peroxide and/or photosensitizer, silane coupling agent,and compounds including epoxy group; and performing a film formation.Therefore, it is possible to form a bridging structure during hardeningand to obtain high adhesion properties, excellent durability andexcellent heat resistance.

In the case that ethylene-vinyl acetate copolymer is used as the polymermentioned above, it is preferred to control a content of vinyl acetatein the ethylene-vinyl acetate copolymer to 10-50 wt % more preferably15-45 wt %. If the content of vinyl acetate is less than 10 wt %, it isnot possible to obtain a sufficient bridging in the case of bridging andhardening at a high temperature. On the other hand, if the content ofvinyl acetate exceeds 50 wt %, a softening temperature of the resin isdecreased and thus it is difficult to stock it.

In the case that copolymer of ethylene-vinyl acetate-acrylate monomerand/or methacrylate monomer is used as the polymer mentioned above, itis preferred to control a content of vinyl acetate in the copolymer to10-50 wt % more preferably 14-45 wt %. If the content of vinyl acetateis less than 10 wt %, it is not possible to obtain a sufficient bridgingin the case of bridging and hardening at a high temperature. On theother hand, if the content of vinyl acetate exceeds 50 wt %, a softeningtemperature of the resin is decreased and thus it is difficult to stockit, so that there is a drawback on actual use. Moreover, it is preferredto control a content of acrylate monomer and/or methacrylate monomer inthe copolymer to 0.01-10 wt % more preferably 0.05-5 wt %. If thecontent of acrylate monomer and/or methacrylate monomer is less than0.01 wt %, an improving effect of an adhesion force is decreased. On theother hand, if the content exceeds 10 wt %, a workability is sometimesdecreased.

As the usable acrylate monomer and/or methacrylate monomer, it ispreferred to use a monomer selected from a group of acrylic estermonomer and methacrylic ester monomer i.e. an ester between acrylic acidor methacrylic acid and a substituent fatty acid with the carbon numberof 1-20 particularly 1-18, which is not substituted or substituted byepoxy group. For example, use is made of methyl acrylate, methylmethacrylate, ethyl acrylate, ethyl methacrylate, glycidyl methacrylateand so on.

In the case that copolymer of ethylene-vinyl acetate-maleic acid and/ormaleic anhydride is used as the polymer mentioned above, it is preferredto control a content of vinyl acetate in the copolymer to 10-50 wt %more preferably 14-45 wt %. If the content of vinyl acetate is less than10 wt %, it is not possible to obtain a sufficient bridging in the caseof bridging and hardening at a high temperature. On the other hand, ifthe content of vinyl acetate exceeds 50 wt %, a strength and adurability of the adhesive layer is extremely deteriorated. Moreover, itis preferred to control a content of maleic acid and/or maleic anhydridein the copolymer to 0.01-10 wt % more preferably 0.05-5 wt %. If thecontent of maleic acid and/or maleic anhydride is less than 0.01 wt %,an improving effect of an adhesion force is decreased. On the otherhand, if the content exceeds 10 wt %, a workability is sometimesdecreased.

In the case that copolymer of ethylene-acrylate monomer and/ormethacrylate monomer-maleic acid and/or maleic anhydride is used as thepolymer mentioned above, it is preferred to control a content ofacrylate monomer in the copolymer to 10-50 wt % more preferably 14-45 wt%. If the content of acrylate monomer is less than 10 wt %, it is notpossible to obtain a sufficient bridging in the case of bridging andhardening at a high temperature. On the other hand, if the content ofacrylate monomer exceeds 50 wt %, a strength and a durability of theadhesive layer is extremely deteriorated. Moreover, it is preferred tocontrol a content of maleic acid and/or maleic anhydride in thecopolymer to 0.01-10 wt % more preferably 0.05-5 wt %. If the content ofmaleic acid and/or maleic anhydride is less than 0.01 wt %, an improvingeffect of an adhesion force is decreased. On the other hand, if thecontent exceeds 10 wt %, a workability is sometimes decreased. It shouldbe noted that the same materials mentioned above are used as theacrylate monomer and/or methacrylate monomer.

In the case that ionomer resin wherein a metal ion is coupled betweenmolecules in ethylene-methacrylic acid copolymer (hereinafter, referredto “ethylene-methacrylic acid ionomer resin”) is used as the polymermentioned above, it is preferred to control a content of methacrylicacid in the resin to 1-30 wt % more preferably 5-25 wt %. If the contentof methacrylic acid is less than 1 wt %, an ion bridging effect isdecreased and thus an adhesion force is decreased. On the other hand, ifthe content exceeds 30 wt %, an extreme deterioration of workabilitysometimes occurs.

As the metal ion used in the ethylene-methacrylic acid ionomer resin,use may be made of a metal cation such as sodium, zinc, magnesium,lithium and so on. Moreover, an ionization degree of metal ion ispreferably 5-80% more preferably 7-70%. If the ionization degree is lessthan 5%, a transparency is extremely deteriorated. If the ionizationdegree exceeds 80%, an extreme deterioration of workability sometimesoccurs.

In order to harden the anisotropic conductive film, it is possible touse organic peroxide and/or photosensitizer. In the case that ahardening adhesive is the thermosetting adhesive, use is made of theorganic peroxide normally. In the case that the hardening adhesive isthe photocuring adhesive, use is made of the photosensitizer normally.

As the organic peroxide added for hardening the anisotropic conductivefilm, any organic peroxide in which radical is generated by dissolvingat a temperature over 70° C. Particularly, it is preferred to used theorganic peroxide in which a dissolving temperature at a half life periodof 10 hours is over 50° C. It is selected on the ground of filmformation temperature, preparing condition, hardening (bonding)temperature, heat resistance of a member to which the film is connected,and storage stability.

As usable organic peroxide, 2,5-dimethlhexane-2,5-dihydroperoxide;2,5-dimethyl-2,5,-di(t-butylperoxy)hexene-3; di-t-butylperoxide;t-butylcumylperoxide; 2,5-dimethyl-2,5-di(t-butylperoxide)hexane;α,α′-bis(t-butylperoxyisopropyl)benzene;n-butyl-4,4′-bis(t-butylperoxy)valerate;1,1-bis(t-butylperoxy)cyclohexane;1,1-bis(t-butylperoxy)-3,3,5-trimethylcyclohexane;t-butylperoxybenzoate; benzoylperoxide; t-butylperoxyacetate;methylethylketoneperoxide; 2,5-dimethylhexyl-2,5-bisperoxybenzoate;butylhydroperoxide; p-menthanehydroperoxide; p-chlorobenzoylperoxide;hydroxyheptylperoxide; chlorohexanoneperoxide; oktanoilperoxide;decanoilperoxide; lauroylperoxide; cumylperoxyoctoate;succinicacidperoxide; acetylperoxide; t-butylperoxy(2-ethylhexanoate);m-toluoylperoxide; benzoylperoxide; 5-butylperoxyisobutylate;2,4-dichlorobenzoylperoxide.

As the organic peroxide, at least one of the above listed peroxides orits compounds are used. Normally, 0.1-10 parts by weight of the organicperoxide is added with respect to 100 parts by weight of the polymermentioned above.

As the photosensitizer (photo polymerization initiator) added forhardening the anisotropic conductive film, radical photo polymerizationinitiator is preferably used. As an hydrogen pull-out initiator amongthe radical photo polymerization initiators, use is made ofbenzophenone; o-benzoilmethylbenzonate;4-benzoil-4′-methyldiphenylsulfide; isopropylthioxanthene;diethylthioxanthene; 4-(diethylamino)ethylbenzoate. Moreover, as anintermolecular splitting initiator among the radical photopolymerization initiators, use is made of benzoilether;benzoilpropylether; benzildimethylketal; α-hydroalkylphenon type such as2-hydroxy-2-methyl-1-phenylpropane-1-on; α-aminoalkylphenon type such as2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropanone-1,2-benzil-2-dimethylamino-1-(4-morpholinophenyl)butane-1;acrylphosphineoxide and so on. As the photosensitizer, at least one ofthe above listed radical photo polymerization initiators or itscompounds are used. Normally, 0.1-10 parts by weight of the radicalphoto polymerization initiator is added with respect to 100 parts byweight of the polymer mentioned above.

As the silane coupling agent added for promoting the adhesion of theanisotropic conductive film, use is made of one material or a compoundmade of two or more materials selected from a group ofvinyltriethoxysilane; vinyltris(β-methoxyethoxy)silane;γ-methacrylicroxypropyltrimetoxysilane; vinyltriacetoxysilane;γ-glycydoxypropyltriethoxysilane; γ-glycydoxypropyltriethoxysilane;β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane; vinyltrichlorosilane;γ-mercaptopropyltrimethoxysilane; γ-aminopropyltrimethoxysilane;γ-aminopropyltriethoxysilane,N-β-(aminoethyl)-aminopropyltrimethoxysilane. An amount of the silanecoupling agent is normally 0.01-5 parts by weight with respect to 100parts by weight of the polymer mentioned above.

As the compound including epoxy group added for promoting the adhesionof the anisotropic conductive film, use is made oftriglycidyltris(2-hydroxyethyl)isocyanurate;neopentylglycoldiglycidylether; 1,6-hexanedioldiglycidylether;acrylglycidylether; 2-ethylhexylglycidylether; phenylglycidylether;phenol(EO)5glycidylether; p-t-butylphenylglycidylether;adipicaciddiglycidylether: phthalicaciddiglycidylether;glycidylmethacrylate; butylglycidylether. Moreover, the same effect canbe obtained by alloying the polymer including epoxy group. The compoundincluding epoxy group is used by itself or as a mixture of two or morekinds of the above compounds, and its amount is normally 0.1-20 parts byweight with respect to 100 parts by weight of the polymer mentionedabove.

In order to improve or control physical properties of the anisotropicconductive film (mechanical strength, adhesion property, opticalproperty, heat resistance, humidity resistance, weather resistance,bridging rate and so on), it is possible to add a compound havingacrylyl group, methacrylyl group or allyl group. As the compound usedfor this purpose, use is normally made of derivatives of acrylic acid ormethacrylic acid such as its ester or its amide, wherein, as an esterresidue, there are alkali group such as methyl, ethyl, dodecyl, stearyl,lauryl; cyclohexyl group; tetrahydro furfuryl group; amino ethyl group;2-hydroxy ethyl group; 3-hydroxy propyl group; 3-chloro-2-hydroxy propylgroup. Moreover, ester with multifunctional alcohol such as ethyleneglycol, triethylene glycol, polypropylene glycol, polyethylene glycol,trimethylolpropane, pentaerythritol can be used in the same manner.Further, as amid, diacetone acrylamide is used typically. Asmultifunctional bridging agents, use is made of ester of acrylic acid ormethacrylic acid such as trimethylolpropane, pentaerythritol, glycerin.Furthermore, as the compound including allyl group, use is made oftriarylcyanulate, triarylisocyanulate, diallyl phthalate, diallylisophthalate, diallyl maleate.

These compounds are used by itself or as a mixture of two or more kinds,and its amount is normally 0.1-50 parts by weight preferably 0.5-30parts by weight with respect to 100 parts by weight of the polymermentioned above.

In the anisotropic conductive film, it is possible to add hydrocarbonresin to adhesives for the purpose of improving workability such as anadhesion operation. In this case, as the hydrocarbon resin to be added,use may be made of natural resin and synthetic resin. As the naturalresin, use may be made of rosin, rosin derivative, terpene base resin.As the rosin, use is made of gum base resin, tall oil base resin, woodbase resin. As the rosin derivative, use may be made of materialsobtained by subjecting rosin to a hydrogenation, a nonuniformitytreatment, a polymerization treatment, an esterufication and ametallization. As the terpene base resin, use may be made of the terpenebase resin such as α-pinene, β-pinene and also terpene phenol resin.Moreover, as the other natural resins, use may be made of dammar, copal,shellac. On the other hand, as the synthetic resin, petroleum baseresin, phenol base resin, xylene base resin are preferably used. As thepetroleum base resin, use may be made of aliphatic petroleum resin,aromatic petroleum resin, copolymerization petroleum resin, pure-monomerpetroleum resin, coumarone-indene resin. As the phenol base resin, usemay be made of alkylphenol resin, denaturized phenol resin. As thexylene base resin, use may be made of xylene resin, denaturalized xyleneresin.

An amount of hydrocarbon resin is suitably selected, but it is preferredto control the amount of hydrocarbon resin to 1-200 parts by weight morepreferably 5-150 parts by weight with respect to 100 parts by weight ofthe polymer mentioned above. Other than the above mentioned additives,use may be made of antioxidant, ultraviolet absorption agent, dye,processing aid to an extent not obstructing the main purpose.

As the conductive particles used in the anisotropic conductive film, usemay be made of various kinds of materials if they show an excellentelectric conductivity. For example, use may be made of a metal powdermade of copper, silver nickel and so on and a resin powder or a ceramicpowder whose surface is coated by the metal mentioned above. Moreover,its shape is not particularly limited, and thus arbitrary shape such assquamation shape, arborized shape, granular shape, pellet shape may beutilized.

An amount of the conductive particles is preferably 0.1-15 vol % withrespect to the polymer mentioned above. Moreover, a particle diameter ofthe conductive particles is preferably 0.1-100 μm more preferably 0.1-20μm. If the amount and the particle diameter are defined in this manner,the conductive particles are not agglutinated between adjacent circuitsand thus a short circuit does not occur.

The anisotropic conductive film is manufactured by adding a bridgingagent (organic peroxide and/or photosensitizer) which generates radicalby applying heat or light as mentioned above, a bridging auxiliary agentaccording to need, a silane coupling agent, compound including epoxybase substance into the polymer mentioned above. That is, theanisotropic conductive film can be manufactured by: mixing evenly thepolymer mentioned above with the additives mentioned above to obtain amixture; kneading the mixture by means of an extruder, a roll and so onto obtain a formed body; and subjecting the formed body to a calendarroll, a T-die extrusion, an inflation so as to obtain the film having apredetermined shape.

In the case of the above film manufacturing, it is possible to performan embossing so as to prevent a blocking and make a pressurizedconnection with an adherend easy. In order to bond the thus obtainedfilm to the adherend (polyimide, copper foil and so on), it is possibleto utilize the known connection methods such as a bonding method bymeans of a heat press, a direct lamination method by means of anextruder or calender, and a connection method with heat and pressure bymeans of a film laminator.

Moreover, it is performed by: dissolving in a solvent which does notaffect the other members; coating evenly on a surface of the member;connecting preliminarily to the adherened (polyimide, copper foil and soon); and hardening by heat or light.

As a hardening condition of the aniostropic conductive film, in the caseof the heat hardening, a temperature is normally 70-170° C. preferably70-150° C. and a time is normally 10 seconds-120 minutes preferably 20seconds-60 minutes; and they depend on a kind of the organic peroxide tobe used.

In the case of the light hardening using the photosensitizer, variouslamps which emit a light from ultraviolet light to visible light can beused as a light source, and use may be normally made of very highpressure mercury lamp, high pressure mercury lamp, low pressure mercurylamp, chemical lamp, xenon lamp, halogen lamp, mercury halogen lamp,carbon arc lamp, incandescent lamp, laser light and so on.

A light emitting time is not decided primarily by a condition such askinds of lamp and light intensity of the light source, but it isnormally several ten seconds to several ten minutes. Moreover, in orderto promote a hardening, a laminated body is preliminarily heated to atemperature of 40-120° C., and the an ultraviolet light is emitted tothe body.

The anisotropic conductive film can be obtained by adding organicperoxide and/or photosensitizer, silane coupling agent, compoundincluding epoxy base substance, together with conductive particles intothe polymer and forming the film.

Since an adhesive of the anisotropic conductive film has the polymermentioned above as a main ingredient, it has the following features: (1)A repair property is excellent; (2) A transparent property is excellent;(3) A high adhesion property is exerted stably as compared with theknown one; (4) A light transmittance property during an electrodepositioning and a workability are excellent, since use is made of thefilm including the transparent polymer mentioned above as a mainingredient; (5) It is possible to perform a hardening connection at alow temperature, since the hardening connection can be performed at atemperature of 100° C. or low while the known epoxy base substance needsa heating over 150° C., and UV hardening can be performed; and (6) Aworkability is excellent, since the anisotropic conductive filmincluding the polymer mentioned above as a main ingredient has a highadhesion force during the preliminarily connection while the knownanisotropic conductive film including epoxy base or phenol basesubstance has no adhesion property and it is difficult to perform apreliminarily adhesion connection between the film and the electrode, sothat it is easy to peel off and a workability is bad.

Then, the first aspect of the invention will be explained in detail withreference to examples according to the invention and comparativeexamples. However, the present invention is not limited to the examplesmentioned below.

EMBODIMENT OF THE FIRST ASPECT OF THE INVENTION EXAMPLE 1 FirstEmbodiment: Particles

A polymer, in which hydroxy group of saturated polyester was substitutedinto metacryoxy group, was used as a base resin. By utilizing the baseresin, a solution, in which 15 wt % of toluene was included, wasprepared. With respect to 100 parts by weight of the base resin, 2 partsby weight of benzoil peroxide, 5 parts by weight of butylated melamineresin (produced by DAINIPPON INK AND CHEMICAL, INCORPORATED, SuperBekkamin L125-60), 3 parts by weight of phosphoric methacrylate(produced by Kyoei Kagaku Kogyo Co., Ltd., PIM), 20 parts by weight ofpolyethylene glycol diacrylate, 0.5 parts by weight ofγ-methacryoxypropyltrimethoxysilane, were added and then mixed to obtaina mixture. Then, 4 parts by weight of conductive particles (produced byNippon Chemical Industrial CO., LTD., 16GNR10.0MX, particle diameter: 5μm) with respect to 100 parts by weight of the base resin was mixed withthe mixture, and cast at 70° C. by means of a roll coater, so that ananisotropic conductive film having a thickness of 20 μm was prepared. Anadhesion force of the thus prepared anisotropic conductive film was 1.2kg/inch when a pressurized connection was performed at 140° C. for 10seconds, and a conductive resistance thereof was 2.5 Ω.

Then, an image display device having a display element with a structureshown in FIG. 1 was prepared. A glass substrate was employed as thetransparent substrate, an epoxy substrate was employed as the opposedsubstrate, and the anisotropic conductive film was employed as thedisplay electrode and the opposed electrode. A fixing operation of theanisotropic conductive film was performed by heating it under 3 MPa at140° C. for 10 seconds. In this case, on the surfaces of respectiveelectrodes, an insulating silicon resin was coated with the thicknessabout 3 μm for the purpose of preventing an adhesion and a chargeleakage. Black toners (spherical toners with average particle diameterof 8 μm, surface charge density of −50 μC/m², the surface potential of450 V at 0.3 second after the foregoing surface potential measurement)for electro-photography were employed as the negatively chargeableparticles. Polymerized particles of styrene-acrylic resin (sphericaltoners with average particle diameter of 8 μm, surface charge density of+45 μC/m², the surface potential of 500 V at 0.3 second after theforegoing surface potential measurement) produced by using titaniumoxide as the white pigment and ammonium salt compound of fourth grade asthe electric charge control agent were employed as the positivelycharge-able particles. For the purpose of charging the particles, anequivalent amount of both particles were mixed and agitated andfrictional charging was conducted. Setting the height of the partitionwalls as 200 μm, the volume population of the particles among the spacebetween the substrates was adjusted to 70%.

When DC voltage of 200 V was applied in such a manner that the displayelectrode was a high potential and the opposed electrode was a lowpotential, the negatively chargeable particles flew and moved towardsthe display electrode, so that a white color was displayed on the imagedisplay element. Then, if the applied voltage was inversed, thenegatively chargeable particles flew and moved towards the opposedelectrode, so that a black color was displayed on the image displayelement.

The response time for the applied voltage was measured to be 1 msec.Even after leaving the display device cutting off the applied voltagefor one day, each display was maintained.

Further, although the polarity of the applied voltage was reversedrepeatedly for 10,000 times, there was almost no variation of theresponse rate.

EXAMPLE 2 First Embodiment: Particles

An image display device was prepared in the same manner as that of theexample 1 except that use was made of 20 parts by weight of neopentylglycol dimethacrylate in spite of 20 parts by weight of polyethyleneglycol diacrylate during the anisotropic film forming in the example 1.

An adhesion force of the anisotropic conductive film was 1.1 kg/inch,and a conductive resistance thereof was 2.5 Ω. The performance of theimage display device was the same as that of the example 1.

REFERENCE EXAMPLE 1 First Embodiment: Particles)

An image display device was prepared in the same manner as that of theexample 1 except that butylated melamine resin and phosphoricmethacrylate were not used during the anisotropic film forming in theexample 1.

An adhesion force of the anisotropic conductive film was 0.4 kg/inch,and a conductive resistance thereof was 2.9 Ω. The performance of theimage display device was the same as that of the example 1.

Then, the image display device utilizing the liquid powders wasdiscussed as the second embodiment of the first aspect of the invention.In this case, physical properties of the liquid powders and functions ofthe image display device according to below examples and comparativeexamples in the first aspect of the invention were estimated inaccordance with following standards.

(1) Particle Diameter Distribution Span and Particle Diameter of theLiquid Powders

Respective liquid powder was installed in Mastersizer 2000 apparatus(Malvern Instruments Ltd.) and the particle diameter distribution Spanwas obtained from the following formula by utilizing attached software(software for calculating the particle size distribution and theparticle size on the basis of a volume standard distribution):Particle diameter distribution Span=(d(0.9)−d(0.1))/d(0.5)(here, d(0.5) means a value of the particle size expressed by μm whereinan amount of the particles having the particle size larger than orsmaller than this value is 50%, d(0.1) means a value of the particlesize expressed by μm wherein an amount of the particles having theparticle size smaller than this value is 10%, and d(0.9) means a valueof the particle size expressed by μm wherein an amount of the particleshaving the particle size smaller than this value is 90%).

The particle diameter (μm) was d(0.5) mentioned above.

(2) Apparent Volume in a Maximum Floating State of the LiquidPowders/Apparent Volume in None Floating State (V_(max)/V₀)

They were measured in accordance with the method described above.

(3) Time Change of Apparent Volume of Liquid Powders (V₁₀/V₅)

They were measured in accordance with the method described above withreference to the apparent volume V₅ (cm³) of the liquid powders after 5minutes from the maximum floating state and the apparent volume Vio(cm³) of the liquid powders after 10 minutes from the maximum floatingstate.

(4) Solvent Insoluble Rate of Liquid Powders

The liquid powder was immersed into MEK solvent for 24 hours at 25° C.and was dried for 5 hours at 100° C. After that, a weight of the liquidpowder was measured. The solvent insoluble rate was measured accordingto the following formula on the basis of a weight deviation of theliquid powder before and after the immersion:solvent insoluble rate (%)=(B/A)×100;(here, A is a weight of the liquid powder before being immersed into thesolvent and B is a weight of liquid powder after the particle isimmersed into MEK solvent at 25° C. for 24 hours).(5) Functional Estimation of the Image Display Device

With respect to the manufactured image display device, the measurementwas performed by increasing the applied voltage and a voltage at whichthe particle started to move so as to display the image was assumed to aminimum drive voltage. Specifically, a voltage at threshold value shownin FIG. 11 was assumed to be the minimum drive voltage.

Then, a voltage of the minimum drive voltage +10 V was applied and apotential was inverted, so that a display of black color-white color wasrepeated.

The estimation of the display function was performed by measuringinitial contrast ratio, contrast ratio after 20000 times repetition andcontrast ration after 5 days left by utilizing a reflection imagedensitometer. Here, the contrast ratio is obtained from the formula:contrast ratio=reflection density at black color display/reflectiondensity at white color display. For reference, contrast ratiomaintaining rates were measured at after 20000 times repetition andafter 5 days left with respect to the initial contrast ratio.

The response rate was measured from a deviation of an output value bymeans of a photomultiplier.

EXAMPLE 3 Second Embodiment: Liquid Powder

(Production of Anisotropic Conductive Film)

A polymer, in which hydroxy group of saturated polyester was substitutedinto metacryoxy group, was used as a base resin. By utilizing the baseresin, a solution, in which 15 wt % of toluene was included, wasprepared. With respect to 100 parts by weight of the base resin, 2 partsby weight of benzoil propylether (photosensitizer), 5 parts by weight ofbutylated melamine resin (produced by DAINIPPON INK AND CHEMICAL,INCORPORATED, Super Bekkamin L125-60), 3 parts by weight of phosphoricmethacrylate (produced by Kyoei Kagaku Kogyo Co., Ltd., PIM), 20 partsby weight of polyethylene glycol diacrylate, 0.5 parts by weight ofγ-methacryoxypropyltrimethoxysilane, were added and then mixed to obtaina mixture. Then, 4 parts by weight of conductive particles (produced byNippon Chemical Industrial CO., LTD., 16GNR10.0MX, particle diameter: 5μm) with respect to 100 parts by weight of the base resin was mixed withthe mixture, and cast at 70° C. by means of a roll coater, so that ananisotropic conductive film having a thickness of 20 μm was prepared. Anadhesion force of the thus prepared anisotropic conductive film was 0.8kg/inch when a pressurized connection was performed at 140° C. for 10seconds, and a conductive resistance thereof was 2.7 Ω.

(Production of Liquid Powder)

Two kinds of the liquid powders (liquid powder X, liquid powder Y) wereprepared.

The liquid powder X was produced as follows. At first, methylmethacrylate monomer, TiO₂ (20 phr), charge control agent bontron E89(Orient Chemical Industries, Ltd.: 5 phr), initiator AIBN (0.5 phr) weresuspended and polymerized. After that, particle sizes of the polymerizedparticles were graded by using a grading device. Then, by usinghybridizer (Nara Machinery Co., Ltd.), the polymerized particles,external additive A (silica H2000/4, Wacker Ltd.) and external additiveB (silica SS20, Japan Silica Ltd.) were set therein and treated at 4800rpm for 5 minuets, so that the external additives were fixed on asurface of the polymerized particles to obtain the liquid powder.

The liquid powder Y was produced as follows. At first, styrene monomer,azo compounds (5 phr), charge control agent bontron N07 (Orient ChemicalIndustries, Ltd.: 5 phr), initiator AIBN (0.5 phr) were suspended andpolymerized. After that, particle sizes of the polymerized particleswere graded by using a grading device. Then, by using hybridizer (NaraMachinery Co., Ltd.), the polymerized particles, external additive A(silica H2050, Wacker Ltd.) and external additive B (silica SS20, JapanSilica Ltd.) were set therein and treated at 4800 rpm for 5 minutes, sothat the external additives were fixed on a surface of the polymerizedparticles to obtain the liquid powder.

The solid state properties of the liquid powder X and the liquid powderY i.e. the above mentioned (1) average particle diameter and particlediameter distribution of the liquid powder, (2) ratio of apparent volumeat maximum floating state of the liquid powder and apparent volume atnone floating state, (3) time change of the apparent volume of theliquid powder (V₁₀/V₅), and (4) solvent insoluble rate of the liquidpowder were shown in table 1.

(Production of Display Device)

At first, a substrate with an electrode, to which the followingpartition wall was formed, was produced.

On a glass substrate to which indium oxide having a thickness of about500 Å was arranged via the above anisotropic conductive film, a ribhaving a height of 250 μm was produced to form a partition wall having astripe shape and a single lever construction.

The production of the rib was performed as follows. As an inorganicpowder, a glass powder was prepared by melting, cooling and grinding amixture of SiO₂, Al₂O₃, B₂O₃, Bi₂O₃, and ZnO. As a resin, epoxy resinhaving heat hardening property was prepared. Then, the glass powder andthe epoxy resin were mixed with a solvent and controlled to be aviscosity of 15000 cps, so that a paste was produced.

Then, the paste was applied on a substrate and heated at 150° C. to behardened. By repeating the above paste applying and heating steps, athickness (corresponding to a height of the partition wall) wascontrolled to be 200 μm (sand blasting method).

Then, a dry photo-resist was adhered. With respect to the adhered dryphoto-resist, an exposing step and an etching step were performed so asto form a mask by which a partition wall pattern having a line of 50 μm,a space of 200 μm and a pitch of 250 μm can be formed.

Then, unnecessary portions were removed by a sandblast to form apredetermined partition wall having a stripe shape.

The liquid powder X was tentatively adhered to the glass substrate onwhich the indium oxide electrode is arranged by means of theelectrostatic coating machine, and the liquid powder Y was tentativelyadhered to another glass substrate. Then, the glass substrates wereopposed with a spacing of 120 μm by using the spacer, and a periphery ofthe glass substrate is connected by means of epoxy adhesive agent, sothat the display device, in which the liquid powder is sealed, wasproduced. The mixing ratio of the liquid powder X and the liquid powderY was controlled to be even, and the filling rate of the liquid powderbetween the glass substrates was controlled to be 60 vol % as the volumeoccupied rate. Here, the gas surrounding the liquid powder in the gapbetween the substrates was an air having a relative humidity of 35% RH.

The estimation results of the display function in the display devicewere shown in the following Table 1.

EXAMPLE 4 Second Embodiment: Liquid Powder

An image display device was produced in the same manner as that of theexample 3 except that the main ingredient in the liquid powder X and theliquid powder Y was changed to urethane (in the liquid powder, carbonwas used together).

The solid state properties of the thus obtained liquid powder X and thethus obtained liquid powder Y and the estimation results of the displayfunctions of the image display device were shown in Table 1.

EXAMPLE 5 Second Embodiment: Liquid Powder

An image display device was produced in the same manner as that of theexample 3 except that an amount of the initiator AIBN in the liquidpowder X and the liquid powder Y was changed to 0.1 phr.

The solid state properties of the thus obtained liquid powder X and thethus obtained liquid powder Y and the estimation results of the displayfunctions of the image display device were shown in Table 1. Since theamount of the initiator AIBN was decreased, the solvent insoluble ratewas decreased and the stability after a lapse of time was ratherdeteriorated.

EXAMPLE 6 Second Embodiment: Liquid Powder

An image display device was produced in the same manner as that of theexample 3 except that the grading operation after the suspension andpolymerize during the production of the liquid powder X and the liquidpowder Y was not performed.

The solid state properties of the thus obtained liquid powder X and thethus obtained liquid powder Y and the estimation results of the displayfunctions of the image display device were shown in Table 2. Since thegrading operation was not performed, the particle diameter distributionSpan was increased and the durability was rather deteriorated.

EXAMPLE 7 Second Embodiment: Liquid Powder

An image display device was produced in the same manner as that of theexample 3 except that the relative humidity in the gap surrounding theliquid powders between the substrates was changed to 80% RH.

The estimation results of the display functions of the image displaydevice were shown in Table 2. Since the humidity of the gap was high,the durability was rather deteriorated.

EXAMPLE 8 Second Embodiment: Liquid Powder

An image display device was produced in the same manner as that of theexample 3 except that the partition walls were not formed. Theestimation results of the display functions of the image display devicewere shown in Table 2. Since the partition walls were not formed, thedurability was rather deteriorated.

COMPARATIVE EXAMPLE 1 Second Embodiment: Liquid Powder

An image display device was produced in the same manner as that of theexample 3 except that the hybridizer operating condition was changed to4800 rpm for 1 minute during the production of the liquid powder X andthe liquid powder Y.

The solid state properties of the thus obtained liquid powder X and thethus obtained liquid powder Y and the estimation results of the displayfunctions of the image display device were shown in Table 3. Since thehybridizer operating condition was changed, a state of the liquidpowders was deteriorated. As a result, the drive voltage was increased,the durability was deteriorated and the response rate became slow.

COMPARATIVE EXAMPLE 2 Second Embodiment: Liquid Powder

An image display device was produced in the same manner as that of theexample 3 except that the hybridizer operating condition was changed to4800 rpm for 30 minutes during the production of the liquid powder X andthe liquid powder Y.

The solid state properties of the thus obtained liquid powder X and thethus obtained liquid powder Y and the estimation results of the displayfunctions of the image display device were shown in Table 3. Since thehybridizer operating condition was changed, a state of the liquidpowders was deteriorated. As a result, the drive voltage was increased,the durability was deteriorated and the response rate became slow.

COMPARATIVE EXAMPLE 3 Second Embodiment: Liquid Powder

An image display device was produced in the same manner as that of theexample 3 except that commercially available toners for xerography wereused as the liquid powder X and the liquid powder Y. The solid stateproperties of the thus obtained liquid powder X and the thus obtainedliquid powder Y and the estimation results of the display functions ofthe image display device were shown in Table 3. Since the toners forxerography were used, a state of the liquid powders was deteriorated. Asa result, the drive voltage was increased, the durability wasdeteriorated and the response rate became slow.

EXAMPLE 9 Second Embodiment: Liquid Powder

An image display device was prepared in the same manner as that of theexample 3 except that use was made of 20 parts by weight of neopentylglycol dimethacrylate in spite of 20 parts by weight of polyethyleneglycol diacrylate during the anisotropic film forming in the example 3.

An adhesion force of the anisotropic conductive film was 0.7 kg/inch,and a conductive resistance thereof was 2.5 Ω. The performance of theimage display device was the same as that of the example 3.

REFERENCE EXAMPLE 2 Second Embodiment: Liquid Powder

An image display device was prepared in the same manner as that of theexample 3 except that butylated melamine resin and phosphoricmethacrylate were not used during the anisotropic film forming in theexample 3.

An adhesion force of the anisotropic conductive film was 0.5 kg/inch,and a conductive resistance thereof was 2.8 Ω. The performance of theimage display device was the same as that of the example 3. TABLE 1Example 3 Example 4 Example 5 Liquid powder X (Material of liquidpowder) Main material MAA monomer urethane MAA monomer TiO₂ TiO₂ TiO₂Initiator (phr) AIBN (0.5) AIBN (0.1) Charge control agent bontron 89bontron 89 bontron 89 Material of external additive A silica H2000/4silica H2000/4 silica H2000/4 Diameter (nm) 20 20 20 Material ofexternal additive B silica SS20 silica SS20 silica SS20 Diameter (nm) 2525 25 External additive adhesion state: processing time of hybridizer(min.) 5 4 5 (Solid state properties of liquid powder) Particle diameter(μm) 3.3 5.2 4.1 Distribution of particle diameter Span 1.6 1.9 1.8V_(max)/V₀ 3.1 2.5 2.6 V₁₀/V₅ 0.91 0.88 0.87 Solvent insoluble rate (%)92 92 48 Liquid powder Y (Material of liquid powder) Main materialstyrene urethane styrene monomer monomer azo-series carbon azo-seriescompound compound Initiator (phr) AIBN(0.5) AIBN(0.1) Charge controlagent bontron 07 bontron 07 bontron 07 Material of external additive Asilica H2050 silica H2050 silica H2050 Diameter (nm) 20 20 20 Materialof external additive B silica SS20 silica SS20 silica SS20 Diameter (nm)25 25 25 External additive adhesion state: processing time of hybridizer(min.) 5 7 5 (Solid state properties of liquid powder) Particle diameter(μm) 3.1 5.1 4.2 Distribution of particle diameter Span 1.7 2.0 1.9V_(max)/V₀ 3.2 2.6 2.7 V₁₀/V₅ 0.92 0.88 0.88 Solvent insoluble rate (%)92 92 49 Relative humidity of gap gas (%) 35 35 35 Partition wallexistence existence existence (Estimation of display function) Minimumdrive voltage (V) 20 23 24 Initial contrast ratio 9.2 7.8 9.2 Contrastratio after 20000 times 8.37 6.94 8.00 Maintaining rate (%) 91 89 87Contrast rate after 5 days left 8.91 6.79 6.35 Maintaining rate (%) 8987 69 Response rate (m/sec) 0.1 0.2 0.3

TABLE 2 Example 6 Example 7 Example 8 Liquid powder X (Material ofliquid powder) Main material MAA monomer MAA monomer MAA monomer TiO₂TiO₂ TiO₂ Initiator (phr) AIBN (0.5) AIBN (0.5) AIBN (0.1) Chargecontrol agent bontron 89 bontron 89 bontron 89 Material of externaladditive A silica H2000/4 silica H2000/4 silica H2000/4 Diameter (nm) 2020 20 Material of external additive B silica SS20 silica SS20 silicaSS20 Diameter (nm) 25 25 25 External additive adhesion state: processingtime of hybridizer (min.) 5 5 5 (Solid state properties of liquidpowder) Particle diameter (μm) 4.2 3.3 3.3 Distribution of particlediameter Span 5.1 1.6 1.6 V_(max)/V₀ 2.1 3.1 3.1 V₁₀/V₅ 0.81 0.91 0.91Solvent insoluble rate (%) 91 92 92 Liquid powder Y (Material of liquidpowder) Main material styrene styrene styrene monomer monomer monomerazo-series azo-series azo-series compound compound compound Initiator(phr) AIBN(0.5) AIBN(0.5) AIBN(0.5) Charge control agent bontron 07bontron 07 bontron 07 Material of external additive A silica H2050silica H2050 silica H2050 Diameter (nm) 20 20 20 Material of externaladditive B silica SS20 silica SS20 silica SS20 Diameter (nm) 25 25 25External additive adhesion state: processing time of hybridizer (min.) 55 5 (Solid state properties of liquid powder) Particle diameter (μm) 4.33.1 3.1 Distribution of particle diameter Span 5.2 1.7 1.7 V_(max)/V₀2.0 3.2 3.2 V₁₀/V₅ 0.80 0.92 0.92 Solvent insoluble rate (%) 91 92 92Relative humidity of gap gas (%) 35 35 35 Partition wall existenceexistence existence (Estimation of display function) Minimum drivevoltage (V) 42 38 21 Initial contrast ratio 9.0 8.8 9.2 Contrast ratioafter 20000 times 7.38 7.04 7.73 Maintaining rate (%) 82 80 84 Contrastrate after 5 days left 7.20 6.07 7.36 Maintaining rate (%) 70 69 80Response rate (m/sec) 1.1 2.1 0.2

TABLE 3 Comparative Comparative Comparative Example 1 Example 2 Example3 Liquid powder X (Material of liquid powder) Main material MAA monomerMAA monomer commercially available toner (yellow) TiO₂ TiO₂ Initiator(phr) AIBN (0.5) AIBN (0.5) Charge control agent bontron 89 bontron 89Material of external additive A silica H2000/4 silica H2000/4 Diameter(nm) 20 20 Material of external additive B silica SS20 silica SS20Diameter (nm) 25 25 External additive adhesion state: processing time ofhybridizer (min.) 1 30 (Solid state properties of liquid powder)Particle diameter (μm) 4.7 4.9 7.2 Distribution of particle diameterSpan 2.2 1.8 1.8 V_(max)/V₀ 1.2 1.2 1.2 V₁₀/V₅ 0.69 0.58 0.68 Solventinsoluble rate (%) 91 92 90 Liquid powder Y (Material of liquid powder)Main material styrene styrene commercially monomer monomer availabletoner (black) azo-series azo-series compound compound Initiator (phr)AIBN(0.5) AIBN(0.5) Charge control agent bontron 07 bontron 07 Materialof external additive A silica H2050 silica H2050 Diameter (nm) 20 20Material of external additive B silica SS20 silica SS20 Diameter (nm) 2525 External additive adhesion state: processing time of hybridizer(min.) 1 30 (Solid state properties of liquid powder) Particle diameter(μm) 4.8 5.0 6.9 Distribution of particle diameter Span 2.2 1.8 1.8V_(max)/V₀ 1.2 1.2 1.2 V₁₀/V₅ 0.69 0.59 0.70 Solvent insoluble rate (%)92 90 90 Relative humidity of gap gas (%) 35 35 35 Partition wallabsence existence existence (Estimation of display function) Minimumdrive voltage (V) 95 88 125 Initial contrast ratio 8.8 9 6.7 Contrastratio after 20000 times 4.93 4.59 3.35 Maintaining rate (%) 56 51 50Contrast rate after 5 days left 4.40 4.32 3.15 Maintaining rate (%) 7048 47 Response rate (m/sec) 11.0 8.1 8.9

AS TO THE SECOND ASPECT OF THE INVENTION

The feature of the image display device according to the second aspectof the invention is to integrate the image display panel and the opticalfunction member through a transparent elastic layer.

In the image display device integrated with the optical function member,if a stress is applied to the screen, a strain occurs thereon and thusthere is a drawback such that an image on the screen is distorted.Particularly, this distortion occurs remarkably in the case that thescreen is formed by the image display panel. Therefore, in the knownimage display device integrated with the optical function member, theoptical function member and the image display panel are connectedthrough spacers to make a gap of about 0.4 mm between them, so that astress is not applied to the screen.

However, such gap causes a scattering and absorbing of the reflectedlight, and thus a contrast ratio, which is important as the display, isdecreased drastically. In addition, there is a drawback on a decrease ofvisibility, a parallax feeling when the image starts to display, ageneration of a display shadow.

The present invention is achieved to eliminate the drawbacks mentionedabove and has for its object to provide the image display deviceintegrated with the optical function member, in which the opticalfunction member such as an anti-reflection glass and the display panelcan be connected with no gap, a light transmittance state is excellent,the decrease of constant ratio can be prevented, and the displayperformance is excellent.

As the optical function member in the image display device according tothe invention, use may be made of the known one, for example, ananti-reflection glass having a light transmittance state, ananti-reflection film, an anti-static glass, an anti-static film, a radiowave shield member, a near-infrared ray absorbing film, a color filter,a touch panel, a protect panel for portable phone. As a material, usemay be made of polycarbonate, glass, acrylic resin. These opticalfunction members can be selected and used suitably as usage of the imagedisplay device according to the invention.

As the transparent elastic layer in the image display device accordingto the invention, use may be made of the known one if its refractionindex is controlled in the manner mentioned below, i.e., as a mainmember, use may be made of polyisoprene, synthetic rubber such aspolybutadiene, olefin base elastomer such as EVA, polyurethane baseelastomer, polyvinyl butyral, vinyl chloride base elastomer, styrenebase elastomer such as SBS, SIS, acryl base resin, silicon base polymer.Particularly, the use of acryl base resin is recommended.

In the transparent elastic layer of the image display device accordingto the invention, the above materials are recommended to use as a mainmember. According to need, the other materials may be added. As theother materials to be added together with the main member, use may bemade of organic peroxide, photosensitizer, elasticizer, adhesionpromotion agent, hydrocarbon resin, antioxidant (polymerizationprevention agent, oxidation inhibitor, ultraviolet absorption agent andso on), the other inorganic or organic filler. Moreover, an effectiveamount of the known fire retardant agent of inorganic base, halogen baseand phosphorous base may be added. In this case, 0.1-50 parts by weightof these materials may be normally added in accordance with its purposewith respect to 100 parts by weight of the main member.

The transparent elastic layer may be formed by directly coating theabove materials to the member, or, may be formed by means of the knownfilm forming method such as calender roll, T-die extrusion, inflation soas to obtain a film shape. In this case, a thickness of the transparentelastic layer is preferably 0.01-5 mm more preferably 0.05-3 mm.

In the image display device according to the invention, when it isassumed that a refractive index of the transparent elastic layer is n₀,a refractive index of the optical function member is n₁ and a refractiveindex of the transparent substrate is n₂, it is necessary to control therefractive index of the transparent elastic layer n₀ with respect to therefractive index of the optical function member is n₁ and the refractiveindex of the transparent substrate is n₂. Particularly, it is preferredto set an absolute of a difference between n₀ and n₁ and an absolute ofa difference between n₀ and n₂ to not greater than 0.2 respectively morepreferably not greater than 0.1 respectively.

By effectively controlling these refractive indexes, it is possible toachieve an excellent light transmittance state, prevent a decrease ofthe contrast ratio and obtain an excellent display property certainly.If these differences between the refractive indexes are too large, areflection property becomes larger and a visibility is decreased.

In the transparent elastic layer according to the invention, it ispreferred that, when it is assumed that a strain (ε₀) at 25° C. of astress relaxation is 5% and an initial value (after 0.05 sec) of astress relaxation elastic modulus is G₀, G₀ is not greater than 6.5×10⁶Pa more preferably not greater than 5.5×10⁶ Pa. In addition, it ispreferred to set a lower limit to not less than 4.0×10⁶ Pa.

By controlling the initial value of the stress relaxation elasticmodulus G₀ in this range, if a surface of a protection panel and so onis pressed, the display portion is not affected, so that it is possibleto certainly prevent a distortion of the display portion, a colorshading and so on. If exceeding the above range, it is not possible toprevent a distortion of the display panel and thus the display panel isliable to be fractured. If it is less than the lower limit, a mechanicalstrength after the connection is not sufficient and thus a decrease ofthe heat resistance sometimes occurs.

Moreover, in the transparent elastic layer according to the invention,it is preferred that a stress relaxation time τ calculated on the basisof a formula:InG(t)=−t/τ+InG ₀showing a relation between a stress relaxation elastic modulus G and atime t (sec.) obtained from a damping curve of the relaxation elasticmodulus, is not greater than 17 sec more preferably not greater than 12sec. In addition, it is preferred to set a lower limit to not less than7 sec.

By controlling the stress relaxation time in this manner, it is possibleto certainly reduce a distortion of the display portion. In addition, itis possible to certainly prevent a generation of the color shading etc.on the display screen of the image display device. In this case, if therelaxation time exceeds the above range, it is not possible to reduce astatic distortion and thus the color shading is liable to occur.

In order to obtain the image display device integrated with the opticalfunction member, so long as the image display panel and the opticalfunction member are integrated through the transparent elastic member,the manufacturing method is not limited particularly. For example, usemay be made of a method in which the transparent elastic layer ispreliminarily formed in accordance with the above method and areconnected by using a predetermined additive, or, a method in which amelted material of the transparent elastic layer is coated on onesurface of the optical function member or the image display panel andthe other one is connected thereto so as to integrate them. As theintegrating method, use may be made of the known method such as a vacuumpress method, a nip roll method and so on. In the case that an airremains at a boundary, a liquid adhesive may be used together with theabove integrating method, or, use may be made of a method in which apressurized heating is utilized by an autoclave and so on.

Then, the second aspect of the invention will be explained in detailwith reference to examples according to the invention and comparativeexamples. However, the present invention is not limited to the examplesmentioned below.

EMBODIMENT OF THE SECOND ASPECT OF THE INVENTION REFERENCE EXAMPLE 1First Embodiment: Particles

An image display device having a display element with a structure shownin FIG. 1 was prepared. A glass substrate was employed as thetransparent substrate, an epoxy substrate was employed as the opposedsubstrate, and a copper electrode was employed as the display electrodeand the opposed electrode. In this case, on the surfaces of respectiveelectrodes, an insulating silicon resin was coated with the thicknessabout 3 μm for the purpose of preventing an adhesion and a chargeleakage. Black toners (spherical toners with average particle diameterof 8 μm, surface charge density of −50 μC/m², the surface potential of450 V at 0.3 second after the foregoing surface potential measurement)for electro-photography were employed as the negatively chargeableparticles. Polymerized particles of styrene-acrylic resin (sphericaltoners with average particle diameter of 8 μm, surface charge density of+45 μC/m², the surface potential of 500 V at 0.3 second after theforegoing surface potential measurement) produced by using titaniumoxide as the white pigment and ammonium salt compound of fourth grade asthe electric charge control agent were employed as the positivelychargeable particles. For the purpose of charging the particles, anequivalent amount of both particles were mixed and agitated andfrictional charging was conducted. Setting the height of the partitionwalls as 200 μm, the volume population of the particles among the spacebetween the substrates was adjusted to 70%.

When DC voltage of 200 V was applied in such a manner that the displayelectrode was a high potential and the opposed electrode was a lowpotential, the negatively chargeable particles flew and moved towardsthe display electrode, so that a white color was displayed on the imagedisplay element. Then, if the applied voltage was inversed, thenegatively chargeable particles flew and moved towards the opposedelectrode, so that a black color was displayed on the image displayelement.

The response time for the applied voltage was measured to be 1 msec.Even after leaving the display device cutting off the applied voltagefor one day, each display was maintained. Further, although the polarityof the applied voltage was reversed repeatedly for 10,000 times, therewas almost no variation of the response rate.

As to an amount of a transmitted light, a light beam was applied to asurface of the thus obtained image display panel from a light and areflected light was measured by a luminance meter, so that a standardvalue (100%) was defined by an amount of the reflected light at thattime.

EXAMPLE 11 First Embodiment: Particles

The image display panel obtained in accordance with the referenceexample 11 was used as the display portion, and a glass transparentsubstrate having a refractive index n₂=1.49 was arranged on bothsurfaces. On one transparent substrate of the display panel, acryl baseadhesive (produced by Soken Chemical & Engineering Co., Ltd., productname SK-DYNE 1831) was coated as the transparent elastic layer, and apolycarbonate protection window (thickness: 1.5 mm, refractive indexn₁=1.59) was adhered on the coated surface as the optical functionmember, so that the image display device integrated with the opticalfunction member was manufactured.

The thus formed transparent elastic layer had properties such asthickness: 0.5 mm, refractive index n₀=1.49, G₀=5.5×10⁶ Pa and stressrelaxation time: 12 seconds.

An amount of a transmitted light in this image display device integratedwith the optical function member was 95%, in the case that the reflectedlight amount of the reference example 11 was assumed to the standardvalue (100%).

COMPARATIVE EXAMPLE 11 First Embodiment: Particles

On the transparent substrate of the image display panel obtained inaccordance with the reference example 11, the polycarbonate protectionwindow as is the same as the example 11 was adhered through a spacer(height: 0.5 mm) by means of the known method, the image display deviceintegrated with the optical function member was manufactured in which anair gap having a thickness of 0.5 mm was arranged between thetransparent substrate of the image display panel and the polycarbonateprotection window. An amount of a transmitted light in this imagedisplay device integrated with the optical function member was 87%, inthe case that the reflected light amount of the reference example 11 wasassumed to the standard value (100%).

Then, as the second embodiment of the second aspect of the invention,the image display panel utilizing the liquid powders was examined. Itshould be noted that the physical properties of the liquid powders andthe functions of the display device in examples and comparative examplesaccording to the following second aspect of the invention were estimatedin accordance with the same standard as those of the above-mentionedfirst aspect of the invention.

REFERENCE Example 12 Second Embodiment: Liquid Powder

(Production of Liquid Powder)

Two kinds of the liquid powders (liquid powder X, liquid powder Y) wereprepared.

The liquid powder X was produced as follows. At first, methylmethacrylate monomer, TiO₂ (20 phr), charge control agent bontron E89(Orient Chemical Industries, Ltd.: 5 phr), initiator AIBN (0.5 phr) weresuspended and polymerized. After that, particle sizes of the polymerizedparticles were graded by using a grading device. Then, by usinghybridizer (Nara Machinery Co., Ltd.), the polymerized particles,external additive A (silica H2000/4, Wacker Ltd.) and external additiveB (silica SS20, Japan Silica Ltd.) were set therein and treated at 4800rpm for 5 minuets, so that the external additives were fixed on asurface of the polymerized particles to obtain the liquid powder.

The liquid powder Y was produced as follows. At first, styrene monomer,azo compounds (5 phr), charge control agent bontron N07 (Orient ChemicalIndustries, Ltd.: 5 phr), initiator AIBN (0.5 phr) were suspended andpolymerized. After that, particle sizes of the polymerized particleswere graded by using a grading device. Then, by using hybridizer (NaraMachinery Co., Ltd.), the polymerized particles, external additive A(silica H2050, Wacker Ltd.) and external additive B (silica SS20, JapanSilica Ltd.) were set therein and treated at 4800 rpm for 5 minutes, sothat the external additives were fixed on a surface of the polymerizedparticles to obtain the liquid powder.

The solid state properties of the liquid powder X and the liquid powderY i.e. the above mentioned (1) average particle diameter and particlediameter distribution of the liquid powder, (2) ratio of apparent volumeat maximum floating state of the liquid powder and apparent volume atnone floating state (V_(max)/V₀), (3) time change of the apparent volumeof the liquid powder (V₁₀/V₅), and (4) solvent insoluble rate of theliquid powder were shown as follows. Liquid powder X Liquid powder YLiquid diameter (μm) 3.3 3.1 Liquid diameter distribution Span 1.6 1.7V_(max)/V₀ 3.1 3.2 V₁₀/V₅ 0.91 0.92 Solvent insoluble rate (%) 92 92(Production of Image Display Panel)

At first, a substrate with an electrode, to which the followingpartition wall was formed, was produced.

On a glass substrate to which indium oxide having a thickness of about500 Å was arranged, a rib having a height of 250 μm was produced to forma partition wall having a stripe shape and a single lever construction.

The production of the rib was performed as follows. As an inorganicpowder, a glass powder was prepared by melting, cooling and grinding amixture of SiO₂, Al₂O₃, B₂O₃, Bi₂O₃, and ZnO. As a resin, epoxy resinhaving heat hardening property was prepared. Then, the glass powder andthe epoxy resin were mixed with a solvent and controlled to be aviscosity of 15000 cps, so that a paste was produced.

Then, the paste was applied on a substrate and heated at 150° C. to behardened. By repeating the above paste applying and heating steps, athickness (corresponding to a height of the partition wall) wascontrolled to be 200 μm (sand blasting method).

Then, a dry photo-resist was adhered. With respect to the adhered dryphoto-resist, an exposing step and an etching step were performed so asto form a mask by which a partition wall pattern having a line of 50 μm,a space of 200 μm and a pitch of 250 μm can be formed.

Then, unnecessary portions were removed by a sandblast to form apredetermined partition wall having a stripe shape.

The liquid powder X was tentatively adhered to the glass substrate onwhich the indium oxide electrode is arranged by means of theelectrostatic coating machine, and the liquid powder Y was tentativelyadhered to another glass substrate. Then, the glass substrates wereopposed with a spacing of 120 μm by using the spacer, and a periphery ofthe glass substrate is connected by means of epoxy adhesive agent, sothat the display device, in which the liquid powder is sealed, wasproduced. The mixing ratio of the liquid powder X and the liquid powderY was controlled to be even, and the filling rate of the liquid powderbetween the glass substrates was controlled to be 60 vol % as the volumeoccupied rate. Here, the gas surrounding the liquid powder in the gapbetween the substrates was an air having a relative humidity of 35% RH.

The thus obtained image display device had the display functions such asminimum drive voltage: 20 V, initial contrast ratio of reflectiondensity at black color display/reflection density at white colordisplay: 9.2 and response rate: 0.1 msec.

Moreover, the contrast ratio after 20000 times repetition was 8.37(maintaining rate: 91%) and the contrast ratio after 5 days left was8.19 (maintaining rate: 89%).

As to an amount of a transmitted light, a light beam was applied to asurface of the thus obtained image display panel from a light and areflected light was measured by a luminance meter, so that a standardvalue (100%) was defined by an amount of the reflected light at thattime.

EXAMPLE 12 Second Embodiment: Liquid Powder

The image display panel obtained in accordance with the referenceexample 12 was used as the display portion, and a glass transparentsubstrate having a refractive index n₂=1.49 was arranged on bothsurfaces. On one transparent substrate of the display panel, acryl baseadhesive (produced by Soken Chemical & Engineering Co., Ltd., productname SK-DYNE 1831) was coated as the transparent elastic layer, and apolycarbonate protection window (thickness: 1.5 mm, refractive indexn₁=1.59) was adhered on the coated surface as the optical functionmember, so that the image display device integrated with the opticalfunction member was manufactured.

The thus formed transparent elastic layer had properties such asthickness: 0.5 mm, refractive index n₀=1.49, G₀=5.5×10⁶ Pa and stressrelaxation time: 12 seconds.

An amount of a transmitted light in this image display device integratedwith the optical function member was 95%, in the case that the reflectedlight amount of the reference example 12 was assumed to the standardvalue (100%).

COMPARATIVE EXAMPLE 12 Second Embodiment: Liquid Powder

On the transparent substrate of the image display panel obtained inaccordance with the reference example 12, the polycarbonate protectionwindow as is the same as the example 12 was adhered through a spacer(height: 0.5 mm) by means of the known method, the image display deviceintegrated with the optical function member was manufactured in which anair gap having a thick-ness of 0.5 mm was arranged between thetransparent substrate of the image display panel and the polycarbonateprotection window. An amount of a transmitted light in this imagedisplay device integrated with the optical function member was 87%, inthe case that the reflected light amount of the reference example 12 wasassumed to the standard value (100%).

(As to the Third Aspect of the Invention)

The feature of the image display device according to the third aspect ofthe invention is to arrange an anti-reflection layer having two or morelayers each indicating different refractive index on a surface of thetransparent substrate i.e. outer surface or inner surface or both ofouter surface and inner surface.

Since the anti-reflection layer has plural layers having differentrefractive index i.e. is constructed by stacking a high refractionmaterial and a low refraction material alternately, it is possible toreduce an outer light reflection and transmit a light having apredetermined wavelength, so that a sharp image can be displayed.

The anti-reflection layer prevent a reflection of light having awavelength of 380-780 nm, and it is preferred that a light reflectanceis not greater than 10% more preferably not greater than 8%.

As the low refraction layer in the anti-reflection layer, use may bemade of a conductive silicon carbide as a target and as the highrefraction layer in the anti-reflection layer, use may be made of aconductive titanium oxide as a target, so that the sputtering process isperformed preferably.

That is, since use is made of the conductive silicon carbide as thetarget, it is possible to apply a high power without being fractured.Moreover, since use is made of the conductive titanium oxide and theconductive silicon carbide as the target, a film forming rate can bemade larger.

Moreover, it is preferred that the low refraction layer is formed by asilicon compound indicated by a group of SiC_(x), SiO_(x), SiN_(x),SiC_(x)O_(y), SiC_(x)N_(y), SiO_(x)N_(y), SiC_(x)O_(y)N_(z),particularly SiC_(x)O_(y) (here, x: 0.1-3 preferably 0.5-2.5, y: 0.1-3preferably 0.5-2.5, z: 0.1-3 preferably 0.5-2.5). Further, it ispreferred that the high refraction layer is formed by TiO_(t) (here, t:0.1-3 preferably 0.5-2.5).

A thickness and the number of stacking the low refraction layer and thehigh refraction layer are designed arbitrarily so as to achieve thedesired property for the anti-reflection film. For example, theanti-reflection film for visible light can be obtained by stacking afirst layer SiC_(x)O_(y) of 15 nm, a second layer TiO_(t) of 30 nm, athird layer of 125 nm and a fourth layer TiO_(t) of 94.5 nm (here, x:0.1-3, y: 0.1-3, t: 0.1-3). In this manner, even if a thickness ofrespective layers is different, the desired property can be arbitrarilyachieved.

As the sputtering method, use may be preferably made of a magnetronsputtering method particularly a dual cathode magnetron sputteringmethod.

In this case, it is preferred that the low refraction layer is formedunder a mixture gas atmosphere of an inert gas and a reactive gas, andas the reactive gas use may be made of a gas in which oxygen is includedin its molecule.

During the sputtering operation, it is necessary not to form a sedimentof the carbon compound in a vacuum chamber and not to include the carboncompound in the transparent conductive layer by making the carboncompound into gas and discharging the gas out of the vacuum chamber.

Sputtering conditions such as a kind of the gas to be supplied, a flowvolume, a pressure, a power to be supplied, can be arbitrarilydetermined with reference to the target to be used, the film formingrate.

In this case, the conductive titanium oxide target means a target havinga volume resistance of not greater than 2×10⁻¹ Ωcm, and the conductivesilicon carbide target means a target having a volume resistance of notgreater than 2×10⁻² Ωcm. If these conductive titanium oxide target andthe conductive silicon carbide target are used, the film forming ratebecomes larger.

As the silicon carbide target, use may be made of the substance obtainedby firing a mixture of silicon carbide powders and nonmetallic firingaids (such as coal tar pitch, phenol resin, furan resin, epoxy resin,glucose, sucrose, cellulose, starchy). It is preferred to use thesilicon carbide target having a density of not less than 2.9 g/cm³. Ifuse is made of the target having a high density and a uniform structure,it is possible to perform a stable discharge even if a high power issupplied during the sputtering, and thus it is possible to make the filmforming rate larger.

In the case that use is made of the silicon carbide target, the carboncompound generated from the silicon carbide becomes gas in the vacuumchamber, and the gas is discharged out of the vacuum chamber. Therefore,there is an effect such that a sediment of the carbon compound is notformed in the vacuum chamber and the carbon compound is not included inthe anti-reflection film during the sputtering operation.

Then, the third aspect of the invention will be explained in detail withreference to examples according to the invention and comparativeexamples. However, the present invention is not limited to the examplesmentioned below.

EMBODIMENT OF THE THIRD ASPECT OF THE INVENTION EXAMPLE 21 FirstEmbodiment: Particles

(Production of Anti-Reflection Film)

On a glass substrate, an anti-reflection layer having two low refractionlayers formed by using the conductive silicon carbide as the target andtwo high refraction layers formed by using the conductive titanium oxideas the target was formed.

The film forming of the low refraction layer was performed by means of amagnetron sputtering apparatus as the sputtering apparatus using theconductive silicon carbide (produced by Bridgestone Corporation,resistance: 2×10−² Ωcm) as the target material under the sputteringconditions such as gas to be supplied: argon gas of 10 cc/min and oxygengas of 3 cc/min, pressure: 5 mTorr, power to be supplied: 1.2 kW.

The film forming of the high refraction layer was performed by means ofa magnetron sputtering apparatus as the sputtering apparatus using theconductive titanium oxide (produced by ASAHI GLASS CO., LTD.,resistance: 2×10⁻¹ Ωcm) as the target material under the sputteringconditions such as gas to be supplied: argon gas of 10 cc/min, pressure:5 mTorr, power to be supplied: 1.2 kW.

Composition, thickness of layer and film forming time of the thusobtained anti-reflection layer were as follows. Film Film Film formingcomposition thickness (nm) time (min) First layer SiC_(0.8)O_(1.2) 15.00.63 Second layer TiO_(1.9) 30.0 0.83 Third layer SiC_(0.8)O_(1.2) 125.05.21 Fourth layer TiO_(1.9) 94.5 2.63 Total film forming time 9.29

An optical performance of the produced anti-reflection layer was shownin FIG. 12.

(Production of Image Display Device)

Then, an image display device having a glass substrate including theanti-reflection layer mentioned above was prepared. An epoxy substratewas employed as the opposed substrate, and the copper electrode wasemployed as the display electrode and the opposed electrode. In thiscase, on the surfaces of respective electrodes, an insulating siliconresin was coated with the thickness about 3 μm for the purpose ofpreventing an adhesion and a charge leakage. Black toners (sphericaltoners with average particle diameter of 8 μm, surface charge density of−50 μC/m², the surface potential of 450 V at 0.3 second after theforegoing surface potential measurement) for electro-photography wereemployed as the negatively chargeable particles. Polymerized particlesof styrene-acrylic resin (spherical toners with average particlediameter of 8 μm, surface charge density of +45 μC/m², the surfacepotential of 500 V at 0.3 second after the foregoing surface potentialmeasurement) produced by using titanium oxide as the white pigment andammonium salt compound of fourth grade as the electric charge controlagent were employed as the positively chargeable particles. For thepurpose of charging the particles, an equivalent amount of bothparticles were mixed and agitated and frictional charging was conducted.Setting the height of the partition walls as 200 μm, the volumepopulation of the particles among the space between the substrates wasadjusted to 70%.

When DC voltage of 200 V was applied in such a manner that the displayelectrode was a high potential and the opposed electrode was a lowpotential, the negatively chargeable particles flew and moved towardsthe display electrode, so that a white color was displayed on the imagedisplay element. Then, if the applied voltage was inversed, thenegatively chargeable particles flew and moved towards the opposedelectrode, so that a black color was displayed on the image displayelement.

The response time for the applied voltage was measured to be 1 msec.Even after leaving the display device cutting off the applied voltagefor one day, each display was maintained.

Further, although the polarity of the applied voltage was reversedrepeatedly for 10,000 times, there was almost no variation of theresponse rate.

REFERENCE EXAMPLE 21 First Embodiment: Particles

In the example 21, an anti-reflection layer obtained by stackingalternately two low refraction layers using a silicon as the target andtwo high refraction layers using a titanium as the target was formed onthe glass substrate.

The film forming of the low refraction layer was performed by means of amagnetron sputtering apparatus as the sputtering apparatus using Si asthe target material under the sputtering conditions such as gas to besupplied: argon gas of 5 cc/min and oxygen gas of 5 cc/min, pressure: 5mTorr, power to be supplied: 1.2 kW.

The film forming of the high refraction layer was performed by means ofa magnetron sputtering apparatus as the sputtering apparatus using Ti asthe target material under the sputtering conditions such as gas to besupplied: argon gas of 5 cc/min and oxygen gas of 5 cc/min, pressure: 5mTorr, power to be supplied: 1.2 kW.

The thicknesses of the low refraction layer and the high refractionlayer were same as those of the example 21. The film forming time was asfollows. That is, the first layer was 7.50 minutes, the second layer was10.00 minutes, the third layer was 62.50 minutes, the fourth layer was31.50 minutes and the total film forming time was 111.50 minutes.

In the image display device according to the invention, it is found fromthe example 21 that a rapid response rate and an excellent stability canbe obtained and that, since the refraction index of the visible light isextremely low in the anti-reflection layer, a sharp image can beobtained.

Moreover, the film forming time of the reference example 21 takes abouttwo hours, but the film forming time of the example 21 takes about 9.50minutes to form the anti-reflection layer having four layers. Therefore,it is found that the anti-reflection layer can be formed in an extremelyshort time if use is made of the silicon carbide for the target of thelow refraction layer and the titanium oxide for the target of the highrefraction layer.

Then, as the second embodiment of the third aspect of the invention, theimage display panel utilizing the liquid powders was examined. It shouldbe noted that the physical properties of the liquid powders and thefunctions of the display device in examples and comparative examplesaccording to the following third aspect of the invention were estimatedin accordance with the same standard as those of the above-mentionedfirst aspect of the invention.

EXAMPLE 22 Second Embodiment: Liquid Powder

(Production of Anti-Reflection Film)

On a glass substrate, an anti-reflection layer having two low refractionlayers formed by using the conductive silicon carbide as the target andtwo high refraction layers formed by using the conductive titanium oxideas the target was formed.

The film forming of the low refraction layer was performed by means of amagnetron sputtering apparatus as the sputtering apparatus using theconductive silicon carbide (produced by Bridgestone Corporation,resistance: 2×10⁻² Ωcm) as the target material under the sputteringconditions such as gas to be supplied: argon gas of 10 cc/min and oxygengas of 3 cc/min, pressure: 5 mTorr, power to be supplied: 1.2 kW.

The film forming of the high refraction layer was performed by means ofa magnetron sputtering apparatus as the sputtering apparatus using theconductive titanium oxide (produced by ASAHI GLASS CO., LTD.,resistance: 2×10⁻¹ Ωcm) as the target material under the sputteringconditions such as gas to be supplied: argon gas of 10 cc/min, pressure:5 mTorr, power to be supplied: 1.2 kW.

Composition, thickness of layer and film forming time of the thusobtained anti-reflection layer were as follows. Film Film Film formingcomposition thickness (nm) time (min) First layer SiC_(0.8)O_(1.2) 15.00.63 Second layer TiO_(1.9) 30.0 0.83 Third layer SiC_(0.8)O_(1.2) 125.05.21 Fourth layer TiO_(1.9) 94.5 2.63 Total film forming time 9.29

An optical performance of the produced anti-reflection layer was shownin FIG. 12.

(Production of Liquid Powder)

Two kinds of the liquid powders (liquid powder X, liquid powder Y) wereprepared.

The liquid powder X was produced as follows. At first, methylmethacrylate monomer, TiO₂ (20 phr), charge control agent bontron E89(Orient Chemical Industries, Ltd.: 5 phr), initiator AIBN (0.5 phr) weresuspended and polymerized. After that, particle sizes of the polymerizedparticles were graded by using a grading device. Then, by usinghybridizer (Nara Machinery Co., Ltd.), the polymerized particles,external additive A (silica H2000/4, Wacker Ltd.) and external additiveB (silica SS20, Japan Silica Ltd.) were set therein and treated at 4800rpm for 5 minuets, so that the external additives were fixed on asurface of the polymerized particles to obtain the liquid powder.

The liquid powder Y was produced as follows. At first, styrene monomer,azo compounds (5 phr), charge control agent bontron N07 (Orient ChemicalIndustries, Ltd.: 5 phr), initiator AIBN (0.5 phr) were suspended andpolymerized. After that, particle sizes of the polymerized particleswere graded by using a grading device. Then, by using hybridizer (NaraMachinery Co., Ltd.), the polymerized particles, external additive A(silica H2050, Wacker Ltd.) and external additive B (silica SS20, JapanSilica Ltd.) were set therein and treated at 4800 rpm for 5 minutes, sothat the external additives were fixed on a surface of the polymerizedparticles to obtain the liquid powder.

The solid state properties of the liquid powder X and the liquid powderY i.e. the above mentioned (1) average particle diameter and particlediameter distribution of the liquid powder, (2) ratio of apparent volumeat maximum floating state of the liquid powder and apparent volume atnone floating state, (3) time change of the apparent volume of theliquid powder (V₁₀/V₅), and (4) solvent insoluble rate of the liquidpowder were shown as follows. Liquid powder X Liquid powder Y Liquiddiameter (μm) 3.3 3.1 Liquid diameter distribution Span 1.6 1.7V_(max)/V₀ 3.1 3.2 V₁₀/V₅ 0.91 0.92 Solvent insoluble rate (%) 92 92(Production of Image Display Device)

The image display device was manufactured by using a glass substratehaving the anti-reflection layer mentioned above.

At first, a substrate with an electrode, to which the followingpartition wall was formed, was produced. On a glass substrate to whichindium oxide having a thickness of about 500 Å was arranged, a ribhaving a height of 250 μm was produced to form a partition wall having astripe shape and a single lever construction.

The production of the rib was performed as follows. As an inorganicpowder, a glass powder was prepared by melting, cooling and grinding amixture of SiO₂, Al₂O₃, B₂O₃, Bi₂O₃, and ZnO. As a resin, epoxy resinhaving heat hardening property was prepared. Then, the glass powder andthe epoxy resin were mixed with a solvent and controlled to be aviscosity of 15000 cps, so that a paste was produced.

Then, the paste was applied on a substrate and heated at 150° C. to behardened. By repeating the above paste applying and heating steps, athickness (corresponding to a height of the partition wall) wascontrolled to be 200 μm (sand blasting method).

Then, a dry photo-resist was adhered. With respect to the adhered dryphoto-resist, an exposing step and an etching step were performed so asto form a mask by which a partition wall pattern having a line of 50 μm,a space of 200 μm and a pitch of 250 μm can be formed.

Then, unnecessary portions were removed by a sandblast to form apredetermined partition wall having a stripe shape.

The liquid powder X was tentatively adhered to the glass substrate onwhich the indium oxide electrode is arranged by means of theelectrostatic coating machine, and the liquid powder Y was tentativelyadhered to another glass substrate. Then, the glass substrates wereopposed with a spacing of 120 μm by using the spacer, and a periphery ofthe glass substrate is connected by means of epoxy adhesive agent, sothat the display device, in which the liquid powder is sealed, wasproduced. The mixing ratio of the liquid powder X and the liquid powderY was controlled to be even, and the filling rate of the liquid powderbetween the glass substrates was controlled to be 60 vol % as the volumeoccupied rate. Here, the gas surrounding the liquid powder in the gapbetween the substrates was an air having a relative humidity of 35% RH.

The thus obtained image display device had the display functions such asminimum drive voltage: 20 V, initial contrast ratio of reflectiondensity at black color display/reflection density at white colordisplay: 9.2 and response rate: 0.1 msec.

Moreover, the contrast ratio after 20000 times repetition was 8.37(maintaining rate: 91%) and the contrast ratio after 5 days left was8.19 (maintaining rate: 89%).

REFERENCE EXAMPLE 22 Second Embodiment: Liquid Powder

In the example 22, an anti-reflection layer obtained by stackingalternately two low refraction layers using a silicon as the target andtwo high refraction layers using a titanium as the target was formed onthe glass substrate.

The film forming of the low refraction layer was performed by means of amagnetron sputtering apparatus as the sputtering apparatus using Si asthe target under the sputtering conditions such as gas to be supplied:argon gas of cc/min and oxygen gas of 5 cc/min, pressure: 5 mTorr, powerto be supplied: 1.2 kW.

The film forming of the high refraction layer was performed by means ofa magnetron sputtering apparatus as the sputtering apparatus using Ti asthe target under the sputtering conditions such as gas to be supplied:argon gas of 5 cc/min and oxygen gas of 5 cc/min, pressure: 5 mTorr,power to be supplied: 1.2 kW.

The thicknesses of the low refraction layer and the high refractionlayer were same as those of the example 1. The film forming time was asfollows. That is, the first layer was 7.50 minutes, the second layer was10.00 minutes, the third layer was 62.50 minutes, the fourth layer was31.50 minutes and the total film forming time was 111.50 minutes.

In the image display device according to the invention, it is found fromthe example 21 that a rapid response rate, a low driving voltage such as20 V, a simple construction, an inexpensive cost and an excellentstability can be obtained and that, since the contrast ratio is high andthe refraction index of the visible light is extremely low in theanti-reflection layer, a sharp image can be obtained.

Moreover, the film forming time of the reference example 22 takes abouttwo hours, but the film forming time of the example 22 takes about 9.50minutes to form the anti-reflection layer having four layers. Therefore,it is found that the anti-reflection layer can be formed in an extremelyshort time if use is made of the silicon carbide for the target of thelow refraction layer and the titanium oxide for the target of the highrefraction layer.

AS TO THE FOURTH ASPECT OF THE INVENTION

The feature of the image display device according to the fourth aspectof the invention is to connect the transparent substrate 1 and theopposed substrate 2 by using a thermosetting adhesive or a photo-curingadhesive in the image display panel having the structure mentionedabove. With reference to FIGS. 13 a-13 c, the connection between thetransparent substrate 1 and the opposed substrate 2 in the image displaypanel 31 of the image display device according to the invention will beexplained specifically in detail as follows.

At first, two substrates are prepared. That is, as shown in FIG. 13 a,the transparent substrate 1, on which the display electrode 3 isarranged, and the opposed substrate 2, on which the opposed electrode 4is arranged, are prepared. The display electrode 3 is arrangedcorrespondingly to respective image display elements 32, and a gap forsetting the partition wall 7 is arranged between the display electrodes3 and 3. In the same manner, the opposed electrode 4 is arrangedcorresponding to respective image display elements 32, and the partitionwall 7 is arranged between the opposed electrodes 4 and 4.

Then, an adhesive for sealing is prepared, and a particle fillingprocess and an adhesive coating process are performed. At first, as theadhesive, the thermosetting adhesive or the photo-curing adhesive,preferably, an adhesive including one of more groups of compounds havingone of glycidyl group, actylic group and methacrylic group is prepared.If the adhesive is the thermo-setting adhesive or the photo-curingadhesive, any known adhesives may be used. As a preferred example, theadhesive for sealing, in which 40 parts by weight of neopenthyl glycolmethacrylate and 2 parts by weight of benzoil peroxide are added withrespect to 100 parts by weight of TO-SO EVA uletrasen UE750R, isprepared. Then, as shown in FIG. 13 b, the negatively chargeableparticles 5 with a white color and the positively chargeable particles 6with a black color are filled in a space constituting the image displayelement 32 between the partition walls 7, and the thus prepared adhesive33 is coated to a frame portion defined at a periphery of thetransparent substrate 1 by means of a dispenser.

Finally, a setting process of the two substrates and a hardening processof the adhesive for sealing by a heat or a light irradiation areperformed. That is, as shown in FIG. 13 c, the setting is performed byadhering the transparent substrate 1 and the opposed substrate 2 via theadhesive 33. Then, heat or light is applied to the setted substrates inaccordance with a type of the adhesive 33 (as one example, in the caseof the adhesive having the composition mentioned above, heating at 130°C. for 10 minutes) so as to harden the adhesive for sealing. The imagedisplay panel 31 is obtained by performing the processes mentionedabove.

In the embodiments shown in FIGS. 13 a-13 c, three image displayelements 32 are arranged in a cross section shown in these figures, butit is a matter of course that the number is not limited to three.Moreover, in the embodiment mentioned above, the image display panelhaving the construction shown in FIG. 8, in which the display electrode3 is arranged to the transparent substrate 1 and the opposed electrode 4is arranged to the opposed substrate 2, is explained, but it is apparentthat the same effects can be obtained by the image display panel havingthe construction shown in FIG. 7, in which the display electrode 3 andthe opposed substrate 4 are arranged to the opposed substrate 2.

AS TO THE FIFTH ASPECT OF THE INVENTION

The feature of the image display device according to the fifth aspect ofthe invention is to form one or more image display elements by using apartition wall 7 arranged between the transparent substrate 1 and theopposed substrate 2 and to use the partition wall 7 having such a shapethat the bottom width wb at a side of the opposed substrate 2 is largerthan the top width wt at a side of the transparent substrate 1.

FIGS. 15 a and 15 b are longitudinal cross sectional views respectivelyshowing one embodiment of a shape of the partition wall 7 used in theimage display device according to the invention. Normally, as shown inFIG. 15 a, use is made of a trapezoidal shape in a cross section suchthat the bottom width wb at a side of the opposed substrate 2 is largerthan the head width wt, preferably, such that a ratio wt/wb between thetop width wt and the bottom width wb is not greater than 0.5. However,as shown in FIG. 15 b, use may be made of the partition wall having ashape such that the top width wt is substantially 0 and a cross sectionis substantially a triangular shape. If the ratio becomes near 0, thetop width wt becomes near 0. In this case, it is possible to improve aparticle elimination effect and a display area increase effect.

However, if it is too excess, a connection between the transparentsubstrate 1 and the partition wall 7 is sometimes insufficient.Therefore, it is necessary to determine the top width wt with taking theconnection state into consideration.

If the shape of the partition wall 7 is suitably selected in thismanner, it is possible to make an opening rate of the transparentsubstrate 1 larger and to make the display area larger, as compared withthe known image display device in which a cross section of the partitionwall 7 is a rectangular shape and the top width wt of the partition wall7 at a side of the transparent substrate 1 is equal to the bottom widthwb of the partition wall at a side of the opposed substrate 2. Moreover,when the particles are filled in the space of the image display elementsurrounded by the partition wall 7, it is possible to make an openingrate of the space larger. In addition, since a flat portion at the topwidth wt is small, it is possible to decrease the residual particles onthe flat portion mentioned above. Therefore, it is not necessary toremove the residual particles from the flat portion at the top width wtand thus the particle handling during the image display devicemanufacturing can be made simple.

The specific embodiments of the fifth aspect of the invention are shownin FIGS. 14 a-14 c and FIG. 16. The features of the embodiments are tooptimize the shape of the partition wall 7. In the reversible imagedisplay device according to the invention shown in FIGS. 14 a-14 c, thenegatively chargeable particles 5 and the positively chargeableparticles are arranged between the transparent substrate 1 and theopposed substrate 2. Under such a condition, when a voltage is appliedfrom a power source in such a manner that a potential difference isgenerated between a side of the display electrode 3 and a side of theopposed electrode 4, the positively chargeable particles 6 move to theside of the display electrode 3 and the negatively chargeable particles5 move to the side of the opposed electrode 4 by means of Coulomb'sforce. In this case, a display face viewed from a side of thetransparent substrate 1 looks like a color of the positively chargeableparticles 6 as shown in FIG. 14 b. Next, when a voltage is applied insuch a manner that an inverse potential difference is generated betweenthe side of the display electrode 3 and the side of the opposedelectrode 4, the negatively chargeable particles 5 move to the side ofthe display electrode 3 and the positively chargeable particles 6 moveto the side of the opposed electrode 4 by means of Coulomb's force asshown in FIG. 14 c. In this case, the display face viewed from the sideof the transparent substrate 1 looks like a color of the negativelychargeable particles 5.

The display states shown in FIGS. 14 b and 14 c are repeatedlychange-able only by reversing the potentials of the power source, andthus it is possible to change colors on the display face reversibly byreversing the potentials of the power source as mentioned above. Forexample, when the negatively chargeable particles 5 are white color andthe positively chargeable particles 6 are black color, or, when thenegatively chargeable particles 5 are black color and the positivelychargeable particles 5 are white color, a reversible image displaybetween white color and black color can be performed. In this methodaccording to the invention, since the particles are once adhered to theelectrode by means of an imaging force, a display image can bemaintained for a long time after a voltage apply is stopped, therebyshowing an excellent memory property.

In the embodiment shown in FIGS. 14 a-14 c, the electrodes are arrangedin such a manner that both of the display electrode 3 and the opposedelectrode 4 having a different potential are arrange to the opposedsubstrate 2 which is opposed to the transparent substrate 1. As theother electrode arranging method, there is a method such that thedisplay electrode 3 is arranged to the transparent substrate 1 and theopposed electrode 4 is arranged to the opposed substrate 2 as shown inFIG. 16. In this case, it is necessary to use a transparent electrode asthe display electrode 3. In the embodiment shown in FIGS. 14 a-14 c,since both of the display electrode 3 and the opposed substrate 4 can beformed by an opaque electrode, it is possible to use an inexpensive anda low resistance metal electrode such as copper, aluminum and so on.

In this case, the applied outer voltage may be superimposed with adirect current or an alternate current. On the surfaces of respectiveelectrodes, an insulating silicon resin may be coated for the purpose ofpreventing an adhesion and a charge leakage. As the coating layer, useis made of a positively chargeable resin for the negatively chargeableparticles and a negatively chargeable resin for the positivelychargeable particles since a charge of the particles is easy todischarge.

It should be noted that, the explanation is made to a case utilizing theparticles, but the same explanation can be applied to a case utilizingthe liquid powders.

Then, the fifth aspect of the invention will be explained in detail withreference to examples according to the invention and comparativeexamples. However, the present invention is not limited to the examplesmentioned below.

EMBODIMENT OF THE FIFTH ASPECT OF THE INVENTION EXAMPLE 41 FirstEmbodiment: Particles

As shown in FIG. 17, a polycarbonate 41 was stacked on the opposedsubstrate 2 and then a die was transferred by using a mold 42 to form apartition wall structure. The bottom width of the partition wall 7 waslarger than the top width. The particles 5, 6 were filled in thepartition wall structure by means of a scattering method. Normally,before connecting the transparent substrate 1, it was necessary toremove the residual particles from a tip of the partition wall 7.However, in the present invention, since the tip of the partition wall 7was narrow, it was possible to remove the particles 5, 6 easily. Afterfilling the particles in the partition wall structure, a positioningbetween the transparent substrate 1 and the opposed substrate 2 wasperformed. Then, a sealing agent was applied between the transparentsubstrate 1 and the partition wall 7, and the transparent substrate 1and the partition wall 7 were adhered so as to connect them. As aresult, it was possible to obtain the image display device in which thedisplay area was rather large and a connection property between thetransparent substrate 1 and the partition wall 7 was excellent.

EXAMPLE 42 First Embodiment: Particles

As shown in FIG. 18, the mold 42 was pressed to the opposed substrate 2and an acrylic resin of UV hardening type was supplied. UV with a powerof 1000 mJ/cm² was irradiated from a side of the opposed substrate 2(glass substrate) and the resin was hardened, so that the partition wallstructure was formed. The bottom width of the partition wall 7 was stilllarger than the top width as compared with the example 41. The particles5, 6 were filled in the partition wall structure by means of ascattering method. Normally, before connecting the transparent substrate1, it was necessary to remove the residual particles from a tip of thepartition wall 7. However, in the present invention, since the tip ofthe partition wall 7 was narrow, it was possible to remove the particles5, 6 easily. After filling the particles in the partition wallstructure, a positioning between the transparent substrate 1 and theopposed substrate 2 was performed. Then, a sealing agent was appliedbetween the transparent substrate 1 and the partition wall 7, and thetransparent substrate 1 and the partition wall 7 were adhered so as toconnect them. As a result, it was possible to obtain the image displaydevice in which the display area was extremely large and a connectionproperty between the transparent substrate 1 and the partition wall 7was rather excellent.

COMPARATIVE EXAMPLE 41 First Embodiment: Particles

As shown in FIG. 19, the partition wall structure was formed byperforming an exposing process and a developing process according to aphoto lithography method. The particles 5, 6 were filled in thepartition wall structure by means of a scattering method. Normally,before connecting the transparent substrate 1, it was necessary toremove the residual particles from a tip of the partition wall 7.However, in this comparative example, since the tip of the partitionwall 7 was wide, it was necessary to remove the particles 5, 6 and thusthere was a drawback such that the process became complicated.

Then, as the second embodiment of the fifth aspect of the invention, theimage display panel utilizing the liquid powders was examined.

EXAMPLE 43 Second Embodiment: Liquid Powder

As shown in FIG. 17, a polycarbonate 41 was stacked on the opposedsubstrate 2 and then a die was transferred by using a mold 42 to form apartition wall structure. The bottom width of the partition wall 7 waslarger than the top width. The liquid powders 5, 6 were filled in thepartition wall structure by means of a scattering method. Normally,before connecting the transparent substrate 1, it was necessary toremove the residual liquid powders from a tip of the partition wall 7.However, in the present invention, since the tip of the partition wall 7was narrow, it was possible to remove the liquid powders 5, 6 easily.After filling the liquid powders in the partition wall structure, apositioning between the transparent substrate 1 and the opposedsubstrate 2 was performed. Then, a sealing agent was applied between thetransparent substrate 1 and the partition wall 7, and the transparentsubstrate 1 and the partition wall 7 were adhered so as to connect them.As a result, it was possible to obtain the image display device in whichthe display area was rather large and a connection property between thetransparent substrate 1 and the partition wall 7 was excellent.

EXAMPLE 44 Second Embodiment: Liquid Powders

As shown in FIG. 18, the mold 42 was pressed to the opposed substrate 2and an acrylic resin of UV hardening type was supplied. UV with a powerof 1000 mJ/cm⁻¹ was irradiated from a side of the opposed substrate 2(glass substrate) and the resin was hardened, so that the partition wallstructure was formed. The bottom width of the partition wall 7 was stilllarger than the top width as compared with the example 43. The liquidpowders 5, 6 were filled in the partition wall structure by means of ascattering method. Normally, before connecting the transparent substrate1, it was necessary to remove the residual liquid powders from a tip ofthe partition wall 7. However, in the present invention, since the tipof the partition wall 7 was narrow, it was possible to remove the liquidpowders 5, 6 easily. After filling the particles in the partition wallstructure, a positioning between the transparent substrate 1 and theopposed substrate 2 was performed. Then, a sealing agent was appliedbetween the transparent substrate 1 and the partition wall 7, and thetransparent substrate 1 and the partition wall 7 were adhered so as toconnect them. As a result, it was possible to obtain the image displaydevice in which the display area was extremely large and a connectionproperty between the transparent substrate 1 and the partition wall 7was rather excellent.

COMPARATIVE EXAMPLE 42 Second Embodiment: Liquid Powders

As shown in FIG. 19, the partition wall structure was formed byperforming an exposing process and a developing process according to aphoto lithography method. The liquid powders 5, 6 were filled in thepartition wall structure by means of a scattering method. Normally,before connecting the transparent substrate 1, it was necessary toremove the residual liquid powders from a tip of the partition wall 7.However, in this comparative example, since the tip of the partitionwall 7 was wide, it was necessary to remove the liquid powders 5, 6 andthus there was a drawback such that the process became complicated.

AS TO THE SIXTH ASPECT OF THE INVENTION

The feature of the method of manufacturing the image display deviceaccording to the invention is to improve a method of forming thepartition wall 7 constituting the image display element during themanufacturing of the image display device having the constructionmentioned above. That is, as shown in FIG. 20, an adhesive 51 isarranged on a tip of the partition wall 7 formed on the opposedsubstrate 2, and the partition wall 7 and the transparent substrate 1are fixed through the adhesive 51, so that the image display element isformed between the transparent substrate 1 and the opposed substrate 2by means of the partition wall 7. Or, as shown in FIG. 20, partitionwalls 7-1, 7-2 are arranged on the transparent substrate 1 and theopposed substrate 2 respectively, and the adhesive 51 is arranged on atip of one partition wall i.e. here on a tip of the partition wall 7-1.Then, the partition walls 7-1, 7-2 are fixed through the adhesive 51 andthe image display element is formed between the transparent substrate 1and the opposed substrate 22 by means of the partition wall 7. It shouldbe noted that, in the embodiments shown in FIGS. 20 and 21, thenegatively chargeable particles 5, the positively chargeable particles 6and the electrodes 3, 4 are omitted for the simplicity of explanations,but these members are existent in an actual case. Moreover, the sameexplanation can be applied for the liquid powders.

By forming the partition wall 7 in this manner, it is possible to formthe partition wall 7 firmly between the transparent substrate 1 and theopposed substrate 2 and to seal a predetermined amount of the particlescompletely in the space constituting the image display element under acondition such that the leakage of the particles is inhibited.

Then, the sixth aspect of the invention will be explained in detail withreference to examples according to the invention and comparativeexamples. However, the present invention is not limited to the examplesmentioned below.

EMBODIMENT OF THE SIXTH ASPECT OF THE INVENTION EXAMPLE 51 FirstEmbodiment: Particles

As shown in FIG. 22, the partition wall 7 was arranged on the opposedsubstrate 2, and the negatively chargeable particles 5 and thepositively charge-able particles 6 were filled in the space constitutingthe image display element formed between the partition walls 7. Undersuch a condition, a thermosetting adhesive 52 was screen-printed on atip of the partition wall 7, and the transparent substrate 1 waspositioned with respect to the opposed substrate 2. Then, a heat and apressure were applied thereto at 110° C.×20 minutes×0.1 MPa, and thepartition wall 7 and the transparent substrate 1 were connected throughthe adhesive 52. As the thermosetting adhesive 12, use was made of theadhesion of radical polymerization type in which the organic peroxidewas added. Then, the display properties at the initial condition andafter 50 million repetition condition were measured and estimated. Theestimation was performed in such a manner that OD values when a voltageapplied to the image display device were measured by the opticaldensitometer and a difference between maximum OD value and minimum ODvalue was assumed as the contrast ratio. The results were shown in thefollowing Table 4.

EXAMPLE 52 First Embodiment: Particles

As shown in FIG. 23, the partition wall 7 was arranged on the opposedsubstrate 2, and the negatively chargeable particles 5 and thepositively chargeable particles 6 were filled in the space constitutingthe image display element formed between the partition walls 7. Undersuch a condition, a UV hardening adhesive 53 was laminated on an overallsurface of the transparent substrate 1 to which the opposed substrate 2was opposed, and the transparent substrate 1 was positioned with respectto the opposed substrate 2. Then, UV having a power of 1000 mJ/cm² wasirradiated thereto, and the partition wall 7 and the transparentsubstrate 1 were connected through the adhesive 53. Then, the displayproperties at the initial condition and after 50 million repetitioncondition were measured and estimated in the same manner as those of theexample 51. The results were shown in the following Table 4.

COMPARATIVE EXAMPLE 51 First Embodiment: Particles

As shown in FIG. 24, the partition wall 7 was arranged on the opposedsubstrate 2, and the negatively chargeable particles 5 and thepositively charge-able particles 6 were filled in the space constitutingthe image display element formed between the partition walls 7. Undersuch a condition, the adhesive was not arranged to the partition wall,and only the positioning between the transparent substrate 1 and theopposed substrate 2 was performed. Then, the transparent substrate 1 andthe opposed substrate 2 were stacked and connected in such a manner thatthe sealing agent was arranged at corner portions of the transparentsubstrate 1 and the partition wall 7. Then, the display properties atthe initial condition and after 50 million repetition condition weremeasured and estimated in the same manner as those of the example 51.The results were shown in the following Table 4. TABLE 4 Displayproperty after Initial display property 50 million times display Example51 15 13 Example 52 13 12 Comparative 14  3 Example 51

From the results shown in Table 4, in the examples 51, 52 according tothe manufacturing method of the present invention, a contrastdeterioration was not detected at all. Contrary to this, in thecomparative example 51 according to the known manufacturing method,since the particles were moved between the image display elements, anextraordinarily display deterioration was detected.

Then, as the second embodiment of the sixth aspect of the invention, theimage display panel utilizing the liquid powders was examined.

EXAMPLE 53 Second Embodiment: Liquid Powder

As shown in FIG. 22, the partition wall 7 was arranged on the opposedsubstrate 2, and the negatively chargeable liquid powders 5 and thepositively chargeable liquid powders 6 were filled in the spaceconstituting the image display element formed between the partitionwalls 7. Under such a condition, a thermosetting adhesive 52 wasscreen-printed on a tip of the partition wall 7, and the transparentsubstrate 1 was positioned with respect to the opposed substrate 2.Then, a heat and a pressure were applied thereto at 110° C.×20minutes×0.1 MPa, and the partition wall 7 and the transparent substrate1 were connected through the adhesive 52. As the thermosetting adhesive12, use was made of the adhesion of radical polymerization type in whichthe organic peroxide was added. Then, the display properties at theinitial condition and after 50 million repetition condition weremeasured and estimated. The estimation was performed in such a mannerthat OD values when a voltage applied to the image display device weremeasured by the optical densitometer and a difference between maximum ODvalue and minimum OD value was assumed as the contrast ratio. Theresults were shown in the following Table 5.

EXAMPLE 54 Second Embodiment: Liquid Powder

As shown in FIG. 23, the partition wall 7 was arranged on the opposedsubstrate 2, and the negatively chargeable liquid powders 5 and thepositively chargeable liquid powders 6 were filled in the spaceconstituting the image display element formed between the partitionwalls 7. Under such a condition, a UV hardening adhesive 53 waslaminated on an overall surface of the transparent substrate 1 to whichthe opposed substrate 2 was opposed, and the transparent substrate 1 waspositioned with respect to the opposed substrate 2. Then, UV having apower of 1000 mJ/cm² was irradiated thereto, and the partition wall 7and the transparent substrate 1 were connected through the adhesive 53.Then, the display properties at the initial condition and after 50million repetition condition were measured and estimated in the samemanner as those of the example 53. The results were shown in thefollowing Table 5.

COMPARATIVE EXAMPLE 52 Second Embodiment: Liquid Powder

As shown in FIG. 24, the partition wall 7 was arranged on the opposedsubstrate 2, and the negatively chargeable liquid powders 5 and thepositively chargeable liquid powders 6 were filled in the spaceconstituting the image display element formed between the partitionwalls 7. Under such a condition, the adhesive was not arranged to thepartition wall, and only the positioning between the transparentsubstrate 1 and the opposed substrate 2 was performed. Then, thetransparent substrate 1 and the opposed substrate 2 were stacked andconnected in such a manner that the sealing agent was arranged at cornerportions of the transparent substrate 1 and the partition wall 7. Then,the display properties at the initial condition and after 50 millionrepetition condition were measured and estimated in the same manner asthose of the example 53. The results were shown in the following Table5. TABLE 5 Display property after Initial display property 50 milliontimes display Example 53 16 14 Example 54 15 13 Comparative 15 3 Example52

From the results shown in Table 5, in the examples 53, 54 according tothe manufacturing method of the present invention, a contrastdeterioration was not detected at all. Contrary to this, in thecomparative example 52 according to the known manufacturing method,since the particles were moved between the image display elements, anextraordinarily display deterioration was detected.

INDUSTRIALLY APPLICABILITY

It is clearly understood from the above explanations, in the imagedisplay device according to the first aspect of the invention, rapidresponse rate, simple construction, inexpensive cost and excellentstability can be achieved. In addition, since the anisotropic conductivefilm is used for connecting the member such as electrode fortransmitting the signal, which is supplied to the circuits for the imagedisplay, and the substrate; the member such as the electrode can beprovided to the substrate at a low temperature for a short time, and anaffection for the substrate in the case of providing the electrode an soon an be minimized, so that the image display device having excellentproperties can be manufactured effectively.

Moreover, in the image display device according to the second aspect ofthe invention, rapid response rate, simple construction, inexpensivecost and excellent stability can be achieved. In addition, since theimage display panel and the optical function member are integratedthrough a transparent elastic layer, it is possible to certainly preventthe decrease of contrast ratio, the distortion of display screen, thecolor shading and so on, and thus the sharp image can be obtained.

Further, in the image display device according to the third aspect ofthe invention, rapid response rate, simple construction, inexpensivecost and excellent stability can be achieved. In addition, since theouter light reflection can be inhibited, it is possible to obtain thehigh contrast and sharp image.

Furthermore, since the conductive silicon carbide is used as the targetfor the low refraction layer and the conductive titanium oxide is usedas the target for the high refraction layer, it is possible to form theanti-reflection layer for an extremely short time, and theanti-reflection film can be produced easily.

Moreover, in the image display device according to the fourth aspect ofthe invention, since two substrates i.e. a transparent substrate and anopposed substrate are connected by using the thermosetting adhesive orthe photo-curing adhesive, it is possible to harden the adhesive in ashort time by applying a heat or irradiating a light after setting twosubstrates through the adhesive at a predetermined position. As aresult, it is possible to prevent the positional deviation between thesubstrates and the leakage of the particles. Moreover, it is possible toachieve the high image display accuracy of the image display panel.

Further, in the image display device according to the fifth aspect ofthe invention, since the partition wall has such a shape that the bottomwidth wb at a side of the opposed substrate is larger than the top widthwt at a side of the transparent substrate, it is possible to decrease aportion of the partition wall to which the transparent substrate iscontacted and to increase a display area. In addition, when theparticles are filled in the image display elements each surrounded bythe partition wall, it is possible to decrease the particles remained onthe head portion of the partition wall and to achieve the simplehandling of the particles during the manufacturing.

Furthermore, in the method of manufacturing the image display deviceaccording to the sixth aspect of the invention, since the improvementcomprises the steps of: forming the partition wall on one or both of atransparent substrate and an opposed substrate; arranging an adhesive ata tip of the partition wall; and connecting the partition wall and theother substrate or both partition walls through the adhesive, it ispossible to achieve a strong connection between the partition wall andthe substrate or a strong connection between the substrates and toprevent a leakage of the particles almost completely.

1. An image display device, in which one or more groups of particles aresealed between opposed two substrates, at least one of two substratesbeing transparent, and, in which the particles, to which anelectrostatic field is applied, are made to move so as to display animage, characterized in that a member for transmitting a signal, whichis applied to circuits for an image display, is provided to thesubstrate by means of an anisotropic conductive film formed byscattering conductive particles in a thermosetting adhesive or aphoto-curing adhesive.
 2. (canceled)
 3. The image display deviceaccording to claim 1, wherein a diameter of the conductive particlesscattered in the thermosetting adhesive or the photo curing adhesive is0.1-20 μm.
 4. The image display device according to claim 1, wherein thethermosetting adhesive or the photo-curing adhesive includes one or moregroups of compounds having one of glycidyl group, acrylic group andmethacrylic group.
 5. An image display device which comprises an imagedisplay panel and an optical function member, in which one or moregroups of particles are sealed between opposed two substrates, at leastone of two substrates being transparent, and, in which the particles, towhich an electrostatic field produced by two groups of electrodes havingdifferent potentials is applied, are made to move so as to display animage, characterized in that the image display panel and the opticalfunction member are integrated through a transparent elastic layer. 6.The image display device according to claim 5, wherein, when it isassumed that a refractive index of the transparent elastic layer is n₀,a refractive index of the optical function member is n₁ and a refractiveindex of the transparent substrate is n₂, an absolute of a differencebetween n₀ and n₁ and an absolute of a difference between n₀ and n₂ arenot greater than 0.2 respectively.
 7. The image display device accordingto claim 5, wherein the transparent elastic layer has a property suchthat, when it is assumed that a strain (ε₀) at 25° C. of a stressrelaxation is 5% and an initial value (after 0.05 sec) of a stressrelaxation elastic modulus is G₀, G₀ is not greater than 6.5×10⁶ Pa,and, a property such that a stress relaxation time x calculated on thebasis of a formula:InG(t)=−t/T+InG ₀ showing a relation between a stress relaxation elasticmodulus G and a time t (sec) obtained from a damping curve of therelaxation elastic modulus, is not greater than 17 sec.
 8. An imagedisplay device, in which one or more groups of particles are sealedbetween opposed two substrates, at least one of two substrates beingtransparent, and, in which the particles, to which an electrostaticfield produced by two groups of electrodes having different potentialsis applied, are made to move so as to display an image, characterized inthat an anti-reflection layer having plural layers each indicatingdifferent refractive index is arranged on a surface of the transparentsubstrate.
 9. The image display device according to claim 8, wherein theanti-reflection layer is constructed by stacking a low refraction layerproduced by a sputtering process using a conductive silicon carbide as atarget and a high refraction layer produced by a sputtering processusing a conductive titanium oxide as a target.
 10. The image displaydevice according to claim 8, wherein the antireflection layer prevents alight reflection of which wavelength is 380-780 nm and a lightreflection rate is not greater than 10%.
 11. An image display devicewhich comprises an image display panel, in which two or more groups ofparticles having different colors and different charge characteristicsare sealed between opposed two substrates, at least one of twosubstrates being transparent, and, in which the particles, to which anelectrostatic field produced by a pair of electrodes arranged on onesubstrate or both substrates is applied, are made to move so as todisplay an image, characterized in that two substrates of the imagedisplay panel are connected by using a thermosetting adhesive or aphoto-curing adhesive.
 12. The image display device according to claim11, wherein the thermosetting adhesive or the photo-curing adhesiveincludes one or more groups of compounds having one of glycidyl group,acrylic group and methacrylic group.
 13. An image display device whichcomprises an image display panel, in which two or more groups ofparticles having different colors and different characteristics aresealed between opposed two substrates, at least one of two substratesbeing transparent, and, in which the particles, to which anelectrostatic field produced by two groups of electrodes havingdifferent potentials is applied, are made to move so as to display animage, characterized in that one or more image display elements areformed by using a partition wall and the partition wall has such a shapethat a bottom width wb at a side of an opposed substrate is larger thana top width wt at a side of a transparent substrate.
 14. The imagedisplay device according to claim 13, wherein a ratio wt/wb between thebottom width wb at a side of the opposed substrate and the top width wtat a side of the transparent substrate is not greater than 0.5.
 15. Theimage display device according to claim 13, wherein a color of theparticles is white or black.
 16. The image display device according toclaim 1, wherein an average particle diameter of the particles is 0.1-50μm.
 17. The image display device according to claim 1, wherein thedifference of a surface charge density in an absolute value between twogroups of the particles measured by using the same kind of carrier inaccordance with a blow-off method is 5-150 μC/m².
 18. The image displaydevice according to claim 1, wherein the particles are particles inwhich the maximum surface potential, in the case that the surface ofparticles is charged by a generation of Corona discharge caused byapplying a voltage of 8 KV to a Corona discharge device deployed at adistance of 1 mm from the surface of the particles, is greater than 300V at 0.3 second after the Corona discharge.
 19. A method ofmanufacturing an image display device which comprises an image displaypanel, in which two or more groups of particles having different colorsand different characteristics are sealed between opposed two substrates,at least one of two substrates being transparent, in which theparticles, to which an electrostatic field produced by two groups ofelectrodes having different potentials is applied, are made to move soas to display an image, and, in which one or more image display elementsare formed by using a partition wall, characterized in that theimprovement comprises the steps of: forming the partition wall on one orboth of a transparent substrate and an opposed substrate; arranging anadhesive at a tip of the partition wall; and connecting the partitionwall and the other substrate or both partition walls through theadhesive.
 20. The method of manufacturing the image display deviceaccording to claim 19, wherein an average particle diameter of theparticles is 0.1-50 μm.
 21. The method of manufacturing the imagedisplay device according to claim 19, wherein the difference of asurface charge density in an absolute value between two groups of theparticles measured by using the same kind of carrier in accordance witha blow-off method is 5-150 μC/m².
 22. The method of manufacturing theimage display device according to claim 19, wherein the particles areparticles in which the maximum surface potential, in the case that thesurface of particles is charged by a generation of Corona dischargecaused by applying a voltage of 8 KV to a Corona discharge devicedeployed at a distance of 1 mm from the surface of the particles, isgreater than 300 V at 0.3 second after the Corona discharge.
 23. Themethod of manufacturing the image display device according to claim 19,wherein a color of the particles is white or black.
 24. An image displaydevice characterized in that the improvement is manufactured inaccordance with the method of manufacturing the image display device setforth in claim
 19. 25. An image display device, in which the liquidpowders, which indicate a high fluidity in an aerosol state such thatsolid-like substances are suspended in a gas stably as dispersoid, aresealed between opposed two substrates, at least one of two substratesbeing transparent, and, in which the liquid powders arc made to move,characterized in that a member for transmitting a signal, which isapplied to circuits for an image display, is provided to the substrateby means of an anisotropic conductive film.
 26. The image display deviceaccording to claim 25, wherein the anisotropic conductive film is formedby scattering conductive particles in a thermosetting adhesive or aphoto-curing adhesive.
 27. The image display device according to claim26, wherein a diameter of the conductive particles scattered in thethermosetting adhesive or the photo-curing adhesive is 0.1-20 μm. 28.The image display device according to claim 26, wherein thethermosetting adhesive or the photo-curing adhesive includes one or moregroups of compounds having one of glycidyl group, acrylic group andmethacrylic group.
 29. An image display device which comprises an imagedisplay panel and an optical function member, in which the liquidpowders, which indicate a high fluidity in an aerosol state such thatsolid-like substances are suspended in a gas stably as dispersoid, aresealed between opposed two substrates, at least one of two substratesbeing transparent, and, in which the liquid powders are made to move,characterized in that the image display panel and the optical functionmember are integrated through a transparent elastic layer.
 30. The imagedisplay device according to claim 29, wherein, when it is assumed that arefractive index of the transparent elastic layer is n₀, a refractiveindex of the optical function member is n₁ and a refractive index of thetransparent substrate is n₂, an absolute of a difference between n₀ andn₁ and an absolute of a difference between n₀ and n₂ are not greaterthan 0.2 respectively.
 31. The image display device according to claim29, wherein the transparent elastic layer has a property such that, whenit is assumed that a strain (ε₀) at 25° C. of a stress relaxation is 5%and an initial value (after 0.05 sec) of a stress relaxation elasticmodulus is G₀, G₀ is not greater than 6.5×10⁶ Pa, and, a property suchthat a stress relaxation time T calculated on the basis of a formula:InG(t)=−t/r+InG ₀ showing a relation between a stress relaxation elasticmodulus G and a time t (sec) obtained from a damping curve of therelaxation elastic modulus, is not greater than 17 sec.
 32. An imagedisplay device, in which the liquid powders, which indicate a highfluidity in an aerosol state such that solid-like substances aresuspended in a gas stably as dispersoid, are sealed between opposed twosubstrates, at least one of two substrates being transparent, and, inwhich the liquid powders are made to move, characterized in that ananti-reflection layer having plural layers each indicating differentrefractive index is arranged on a surface of the transparent substrate.33. The image display device according to claim 32, wherein theanti-reflection layer is constructed by stacking a low refraction layerproduced by a sputtering process using a conductive silicon carbide as atarget and a high refraction layer produced by a sputtering processusing a conductive titanium dioxide as a target.
 34. The image displaydevice according to claim 32, wherein the anti-reflection layer preventsa light reflection of which wavelength is 380-780 nm and a lightreflection rate is not greater than 10%.
 35. An image display devicewhich comprises an image display panel, in which the liquid powders,which indicate a high fluidity in an aerosol state such that solid-likesubstances are suspended in a gas stably as dispersoid, are sealedbetween opposed two substrates, at least one of two substrates beingtransparent, and, in which the liquid powders, to which an electrostaticfield produced by a pair of electrodes arranged on one substrate or bothsubstrates is applied, are made to move so as to display an image,characterized in that two substrates of the image display panel areconnected by using a thermosetting adhesive or a photo-curing adhesive.36. The image display device according to claim 35, wherein thethermosetting adhesive or the photo-curing adhesive includes one or moregroups of compounds having one of glycidyl group, acrylic group andmethacrylic group.
 37. An image display device which comprises an imagedisplay panel, in which the liquid powders, which indicate a highfluidity in an aerosol state such hat solid-like substances aresuspended in a gas stably as dispersoid, are sealed between opposed twosubstrates, at least one of two substrates being transparent, and, inwhich the liquid powders, to which an electrostatic field produced by apair of electrodes having different potentials is applied, are made tomove so as to display an image, characterized in that one or more imagedisplay elements are formed by using a partition wall and the partitionwall has such a shape that a bottom width wb at a side of an opposedsubstrate is larger than a top width wt at a side of a transparentsubstrate.
 38. The image display device according to claim 37, wherein aratio wt/wb between the bottom width wb at a side of the opposedsubstrate and the top width wt at a side of the transparent substrate isnot greater than 0.5.
 39. The image display device according to claim25, wherein an apparent volume in a maximum floating state of the liquidpowders is two times or more than that in none floating state,
 40. Theimage display device according to claim 25, wherein a time change of theapparent volume of the liquid powders satisfies the following formula:V ₁₀ /V ₅>0.8; here, V₅ indicates the apparent volume (cm³) of theliquid powders after 5 minutes from the maximum floating state; and V₁₀indicates the apparent volume (cm³) of the liquid powders after 10minutes from the maximum floating state.
 41. The image display deviceaccording to claim 25, wherein an average particle diameter d(0.5) ofthe liquid powders is 0.1-20 μm.
 42. A method of manufacturing an imagedisplay device which comprises an image display panel, in which theliquid powders, which indicate a high fluidity in an aerosol state suchthat solid-like substances are suspended in a gas stably as dispersoid,are sealed between opposed two substances, at least one of twosubstrates being transparent, in which the liquid powders, to which anelectrostatic field produced by a pair of electrodes having differentpotentials is applied are made to move so as to display an image, and,in which one or more image display elements are formed by using apartition wall, characterized in that the improvement comprises thesteps of: forming the partition wall on one or both of a transparentsubstrate and an opposed substrate; arranging an adhesive at a tip ofthe partition wall; and connecting the partition wall and the othersubstrate or both partition walls through the adhesive.
 43. The methodof manufacturing the image display device according to claim 42, whereinan apparent volume in a maximum floating state of the liquid powders istwo times or more than that in none floating state.
 44. The method ofmanufacturing the image display device according to claim 42, wherein atime change of the apparent volume of the liquid powders satisfies thefollowing formula:V ₁₀ /V ₅>0.8; here, V₅ indicates the apparent volume (cm³) of theliquid powders after 5 minutes from the maximum floating state; and V₁₀indicates the apparent volume (cm³) of the liquid powders after 10minutes from the maximum floating state.
 45. The method of manufacturingthe image display device according to claim 42, wherein an averageparticle diameter d(0.5) of the liquid powders is 0.1-20 μm.
 46. Animage display device characterized in that the improvement ismanufactured in accordance with the method of manufacturing the imagedisplay device set forth in claim 42.